New articles on Mathematics

[1] 2311.16128

Physics-Inspired Discrete-Phase Optimization for 3D Beamforming with PIN-Diode Extra-Large Antenna Arrays

Large antenna arrays can steer narrow beams towards a target area, and thus improve the communications capacity of wireless channels and the fidelity of radio sensing. Hardware that is capable of continuously-variable phase shifts is expensive, presenting scaling challenges. PIN diodes that apply only discrete phase shifts are promising and cost-effective; however, unlike continuous phase shifters, finding the best phase configuration across elements is an NP-hard optimization problem. Thus, the complexity of optimization becomes a new bottleneck for large-antenna arrays. To address this challenge, this paper suggests a procedure for converting the optimization objective function from a ratio of quadratic functions to a sequence of more easily solvable quadratic unconstrained binary optimization (QUBO) sub-problems. This conversion is an exact equivalence, and the resulting QUBO forms are standard input formats for various physics-inspired optimization methods. We demonstrate that a simulated annealing approach is very effective for solving these sub-problems, and we give performance metrics for several large array types optimized by this technique. Through numerical experiments, we report 3D beamforming performance for extra-large arrays with up to 10,000 elements.

[2] 2311.16167

MMPDE-Net and Moving Sampling Physics-informed Neural Networks Based On Moving Mesh Method

In this work, we propose an end-to-end adaptive sampling neural network (MMPDE-Net) based on the moving mesh PDE method, which can adaptively generate new coordinates of sampling points by solving the moving mesh PDE. This model focuses on improving the efficiency of individual sampling points. Moreover, we have developed an iterative algorithm based on MMPDE-Net, which makes the sampling points more precise and controllable. Since MMPDE-Net is a framework independent of the deep learning solver, we combine it with PINN to propose MS-PINN and demonstrate its effectiveness by performing error analysis under the assumptions given in this paper. Meanwhile, we demonstrate the performance improvement of MS-PINN compared to PINN through numerical experiments on four typical examples to verify the effectiveness of our method.

[3] 2311.16170

Algebraic aspects and functoriality of the set of affiliated operators

In this article, we aim to provide a satisfactory algebraic description of the set of affiliated operators for von Neumann algebras. Let $\mathscr{M}$ be a von Neumann algebra acting on a Hilbert space $\mathcal{H}$, and let $\mathscr{M}_{\text{aff}}$ denote the set of unbounded operators of the form $T = AB^{\dagger}$ for $A, B \in \mathscr{M}$ with $\ker(B)\subseteq\ker(A)$ , where $(\cdot)^{\dagger}$ denotes the Kaufman inverse. We show that $\mathscr{M}_{\text{aff}}$ is closed under product, sum, Kaufman-inverse and adjoint; Moreover, the above quotient representation of an operator in $\mathscr{M}_{\text{aff}}$ is essentially unique. Using a novel, simple, and complete algebraic characterization of closed operators in terms of bounded operators, we observe that the Murray-von Neumann affiliated operators for $\mathscr{M}$ are precisely the closed operators in $\mathscr{M}_{\text{aff}}$. Let $\Phi$ be a unital normal homomorphism between represented von Neumann algebras $(\mathscr{M}; \mathcal{H})$ and $(\mathscr{N}; \mathcal{K})$. With the help of the quotient representation, we obtain a canonical extension of $\Phi$ to a mapping $\Phi_{\text{aff}} : \mathscr{M}_{\text{aff}} \to \mathscr{N}_{\text{aff}}$ which respects sum, product, Kaufman-inverse, and adjoint. Thus $\mathscr{M}_{\text{aff}}$ is intrinsically associated with $\mathscr{M}$ and transforms functorially as we change representations of $\mathscr{M}$. Furthermore, $\Phi_{\text{aff}}$ preserves operator properties such as being symmetric, or positive, or accretive, or sectorial, or self-adjoint, or normal, and also preserves the Friedrichs and Krein-von Neumann extensions of densely-defined closed positive operators. As a proof of concept, we transfer some well-known results about closed unbounded operators to the setting of closed affiliated operators for properly infinite von Neumann algebras, via `abstract nonsense'.

[4] 2311.16177

A hybrid local search algorithm for the Continuous Energy-Constrained Scheduling Problem

We consider the Continuous Energy-Constrained Scheduling Problem (CECSP). A set of jobs has to be processed on a continuous, shared resource. A schedule for a job consists of a start time, completion time, and a resource consumption profile. We want to find a schedule such that: each job does not start before its release time, is completed before its deadline, satisfies its full resource requirement, and respects its lower and upper bounds on resource consumption during processing. Our objective is to minimize the total weighted completion time. We present a hybrid local search approach, using simulated annealing and linear programming, and compare it to a mixed-integer linear programming (MILP) formulation. We show that the hybrid local search approach matches the MILP formulation in solution quality for small instances, and is able to find a feasible solution for larger instances in reasonable time.

[5] 2311.16178

On the difference of initial logarithmic coefficients for the class of univalent functions

In this paper we give estimates of the differences $|\gamma_3|-|\gamma_2|$ and $|\gamma_4|-|\gamma_3|$ for the class of functions $f$ univalent in the unit disc and normalized by $f(0)=f'(0)-1=0$. Here, $\gamma_{2}$, $\gamma_{3}$ and $\gamma_{4}$ are the initial logarithmic coefficients of the function $f$.

[6] 2311.16186

A collection of integrals, products and series

This is a conspectus of definite integrals, products and series. These formulae involve special functions in the integrand and summand functions and closed form solutions. Some of the special cases are stated in terms of fundamental constants.

[7] 2311.16189

Many vertex-disjoint even cycles of fixed length in a graph

For every integer $k \ge 3$, we determine the extremal structure of an $n$-vertex graph with at most $t$ vertex-disjoint copies of $C_{2k}$ when $n$ is sufficiently large and $t$ lies in the interval $\left[\frac{\mathrm{ex}(n,C_{2k})}{\varepsilon n}, \varepsilon n\right]$, where $\varepsilon>0$ is a constant depending only on $k$. The question for $k = 2$ and $t = o\left(\frac{\mathrm{ex}(n,C_{2k})}{n}\right)$ was explored in prior work~\cite{HHLLYZ23a}, revealing different extremal structures in these cases. Our result can be viewed as an extension of the theorems by Egawa~\cite{Ega96} and Verstra\"{e}te~\cite{Ver03}, where the focus was on the existence of many vertex-disjoint cycles of the same length without any length constraints.

[8] 2311.16205

Variational Methods for $p$-Sub-Laplacians on Heisenberg Group

This article serves as my Masters Thesis under the kind supervision of Prof. K. Sreenadh at IIT Delhi, India. The primary objective of this article is to study the existence and compute the multiplicity of non-trivial solutions for the special Kirchhoff-type elliptic equation under certain assumptions of degeneracy and non-degeneracy on the Heisenberg Group, under certain fixed conditions on the Kirchhoff Function $M$, the Potential Function $V$ and $f$, along with the notion of the Mountain Pass Theorem and the Concentration-Compactness Principles for classical Sobolev Spaces on $\mathcal{H}_{n}$. The paper provides a brief albeit lucid exposition on the topic of \textit{Carnot Groups} in terms of connected and simply connected Lie Groups and their associated Lie Algebras that admits a specific stratification. Furthermore, we shall study the specific case of Carnot Groups of Step $2$, also known as the \textit{Heisenberg Group}. One of the significant aspects of this paper is to study the \textit{sub-laplacians} $\mathcal{L}$ and the \textit{twisted laplacians} $L_{\tau}$ on $\mathcal{H}_{3}$ along with observing their spectral behaviour in some detail. Also, the essential self-adjointness of $\mathcal{L}$ as an unbounded linear operator from $L^{2}(\mathcal{H}_{3})$ to $L^{2}(\mathcal{H}_{3})$ having a dense domain $\mathcal{S}(\mathcal{H}_{3})$ ( described in \textit{section $8$} ). \textit{Sections $9$} and $10$ have been devoted towards analyzing the spectrum of the unique self-adjoint extension of the sub-Laplacian on $\mathcal{H}_{3}$. Suitable references have been provided to facilitate interested readers with learning different concepts discussed here in further detail.

[9] 2311.16210

An uncountable union of line segments with null two-dimensional measure

In this paper we construct an uncountable union of line segments $T$ which has full intersection with the sets $(\{ 0\} \times [0, 1]) \cup (\{ 1\} \times [0, 1])\subset\mathbb{R}^2$ but has null two-dimensional measure. Further results are proved on the decay rate of $\mu (T)$ if the line segments comprising $T$ are replaced with increasingly fine approximations by parallelograms.

[10] 2311.16212

Lebesgue's test for general Dirichlet's integrals

It is well-known the Lebesgue \cite{Lebesgue, Zygmund} test for trigonometric Fourier series. Taberski \cite{Taberski1, Taberski2} considered real-valued Lebesgue locally integrable functions $f$, such that \begin{equation*} \lim_{T \to \infty} \frac{1}{T} \int_{T}^{T+c} |f(t)| \, dt\ =0; \quad \lim_{T \to \infty} \frac{1}{T} \int_{-T-c}^{-T} |f(t)| \, dt \ =0 \end{equation*} for every fixed $c>0$. For this class of functions, he defined generalized Dirichlet's integrals. Besides, Taberski \cite{Taberski1,Taberski2} investigated problems of convergence and $(C,1)$-summability of these integrals. In this paper, the analogous of the Lebesgue test for the generalized Dirichlet's integrals is proved.

[11] 2311.16219

Principal Landau Determinants

We reformulate the Landau analysis of Feynman integrals with the aim of advancing the state of the art in modern particle-physics computations. We contribute new algorithms for computing Landau singularities, using tools from polyhedral geometry and symbolic/numerical elimination. Inspired by the work of Gelfand, Kapranov, and Zelevinsky (GKZ) on generalized Euler integrals, we define the principal Landau determinant of a Feynman diagram. We illustrate with a number of examples that this algebraic formalism allows to compute many components of the Landau singular locus. We adapt the GKZ framework by carefully specializing Euler integrals to Feynman integrals. For instance, ultraviolet and infrared singularities are detected as irreducible components of an incidence variety, which project dominantly to the kinematic space. We compute principal Landau determinants for the infinite families of one-loop and banana diagrams with different mass configurations, and for a range of cutting-edge Standard Model processes. Our algorithms build on the Julia package Landau.jl and are implemented in the new open-source package PLD.jl available at

[12] 2311.16255

Theta functions, fourth moments of eigenforms, and the sup-norm problem III

In the prequel, a sharp bound in the level aspect on the fourth moment of Hecke--Maa{\ss} forms with an inexplicit (in fact exponential) dependency on the eigenvalue was given. In this paper, we develop further the framework of explicit theta test functions in order to capture the eigenvalue more precisely. We use this to reduce a sharp hybrid fourth moment bound to an intricate counting problem. Unconditionally, we give a hybrid bound, which is sharp in the level aspect and with a slightly larger than convex dependency on the eigenvalue.

[13] 2311.16256

On the stability of $θ$-methods for DDEs and PDDEs

In this paper, the stability of $\theta$-methods for delay differential equations is studied based on the test equation $y'(t)=-A y(t) + B y(t-\tau)$, where $\tau$ is a constant delay and $A$ is a positive definite matrix. It is mainly considered the case where the matrices $A$ and $B$ are not simultaneosly diagonalizable and the concept of field of values is used to prove a sufficient condition for unconditional stability of these methods and another condition which also guarantees their stability, but according to the step size. The results obtained are also simplified for the case where the matrices $A$ and $B$ are simultaneously diagonalizable and compared with other similar works for the general case. Several numerical examples in which the theory discussed here is applied to parabolic problems given by partial delay differential equations with a diffusion term and a delayed term are presented, too.

[14] 2311.16259

An algebraic criterion for the vanishing of bounded cohomology

We prove the vanishing of bounded cohomology with separable dual coefficients for many groups of interest in geometry, dynamics, and algebra. These include compactly supported structure-preserving diffeomorphism groups of certain manifolds; the group of interval exchange transformations of the half line; piecewise linear and piecewise projective groups of the line, giving strong answers to questions of Calegari and Navas; direct limit linear groups of relevance in algebraic K-theory, thereby answering a question by Kastenholz and Sroka and a question of two of the authors and L\"oh; and certain subgroups of big mapping class groups, such as the stable braid group and the stable mapping class group, proving a conjecture of Bowden. Moreover, we prove that in the recently introduced framework of enumerated groups, the generic group has vanishing bounded cohomology with separable dual coefficients. At the heart of our approach is an elementary algebraic criterion called the commuting cyclic conjugates condition that is readily verifiable for the aforementioned large classes of groups.

[15] 2311.16262

On the Structure of Singularities of Weak Mean Curvature Flows with Mean Curvature Bounds

This paper studies singularities of mean curvature flows with integral mean curvature bounds $H \in L^\infty L^p_{loc}$ for some $p \in ( n, \infty]$. For such flows, any tangent flow is given by the flow of a stationary cone $\mathbf{C}$. When $p = \infty$ and $\mathbf{C}$ is a regular cone, we prove that the tangent flow is unique. These results hold for general integral Brakke flows of arbitrary codimension in an open subset $U \subseteq \mathbb{R}^N$ with $H \in L^\infty L^p_{loc}$. For smooth, codimension one mean curvature flows with $H \in L^\infty L^\infty_{loc}$, we also show that, at points where a tangent flow is given by an area-minimizing Simons cone, there is an accompanying limit flow given by a smooth Hardt-Simon minimal surface.

[16] 2311.16264

On the motivic classification of codimentional filtration quotients

In this note, we study motivic pro-spaces of the form \begin{equation*}\label{eq:XXz}X/(X-x),\end{equation*}where $x\in X$ is the closed point of a local essentially smooth scheme $X$ over a scheme $B$. We obtain some results on the classification up to motivic equivalences with respect to the pointed Morel-Voevodsky $\mathbb{A}^1$-homotopy motivic category $\mathbf{H}^\bullet(B)$, and study some morphisms in between of $\mathbf{H}^\bullet(B)$, and Voevodsky's motives category $\mathbf{DM}(B)$.

[17] 2311.16271

Permittivity optimization for Maxwell's eigenvalues

We formulate an optimization problem for the dependence of the eigenvalues of Maxwell's equations in a cavity upon variation of the electric permittivity and we prove a corresponding Maximum Principle.

[18] 2311.16280

Higher regularity of solutions to elliptic equations on low-dimensional structures

This paper aims to establish counterparts of fundamental regularity statements for solutions to elliptic equations in the setting of low-dimensional structures such as, for instance, glued manifolds or CW-complexes. The main result proves additional Sobolev-type regularity of weak solutions to elliptic problems defined on the low-dimensional structure. Due to the non-standard geometry of a domain, we propose a new approach based on combining suitable extensions of functions supported on the thin structure with uniform bounds for difference quotients. We also derive several important conclusions from that result, namely global continuity of weak solutions and we address the correspondence between the low-dimensional weak problems and the second-order operators widely applied in the framework developed for applications in variational problems.

[19] 2311.16281

The Arithmetic of Elliptic Pairs and An $ν+1$-variable Artin Conjecture

The theory of elliptic pairs, as investigated in a paper by Castravet, Laface, Tevelev, and Ugaglia, provides useful conditions to determine polyhedrality of the pseudo-effective cone, which give rise to interesting arithmetic questions when reducing the variety modulo $p$. In this paper, we examine one such case, namely the blow-up $X$ of 9 points in $\mathbb{P}^2$ lying on the nodal cubic, and study the density of primes $p$ for which the pseudo-effective cone of the reduction of $X$ modulo $p$ is polyhedral. This problem reduces to an analogue of Artin's Conjecture on primitive roots like that investigated by Stephens and then Moree and Stevenhagen. As a result, we find that the density of such "polyhedral primes" hover around a higher analogue of the Stephens' Constant under the assumption of the Generalized Riemann Hypothesis. Finally, in order to determine a precise value for the density of polyhedral primes, we look at the containment of rank 8 root sublattices of $\mathbb{E}_8$.

[20] 2311.16285

Long Time Behavior of Stochastic Thin Film Equation

In this paper we consider a stochastic thin-film equation with a one dimensional Gaussian Stratonovych noise. We establish the existence of non-negative global weak martingale solution, and study its long time asymptotic properties. In particular, we show the solution almost surely converges to the average value of the initial condition. Furthermore, using the regularized equations and adapted entropy functionals, we establish the exponential asymptotic decay of the solution in the uniform norm.

[21] 2311.16287

Cohomology of fixed point sets of anti-symplectic involutions in the Hilbert scheme of points on a surface

Let $S$ be a smooth, quasi-projective complex surface with complex symplectic form $\omega \in H^0(S, K_S)$. This determines a symplectic form $\omega_n$ on the Hilbert scheme of points $S^{[n]}$ for $n \geq 1$. Let $\tau$ be an anti-symplectic involution of $(S,\omega)$: an order two automorphism of $S$ such that $ \tau^*\omega=-\omega$. Then $\tau$ induces an anti-symplectic involution on $(S^{[n]},\omega_n)$ and the fixed point set $(S^{[n]})^\tau$ is a smooth Lagrangian subvariety of $S^{[n]}$. In this paper, we calculate the mixed Hodge structure of $H^*( (S^{[n]})^\tau; \mathbb{Q})$ in terms of the mixed Hodge structures of $H^*( S^\tau;\mathbb{Q})$ and of $H^*( S / \tau; \mathbb{Q})$. We also classify the connected components of $(S^{[n]})^\tau$ and determine their mixed Hodge structures. Our results apply more generally whenever $S$ is a smooth quasi-projective surface, and $\tau$ is an involution of $S$ for which $S^\tau$ is a curve.

[22] 2311.16296

Energy decay rate of a transmission system governed by degenerate wave equation with drift and under heat conduction with memory effect

In this paper, we investigate the stabilization of transmission problem of degenerate wave equation and heat equation under Coleman-Gurtin heat conduction law or Gurtin-Pipkin law with memory effect. We investigate the polynomial stability of this system when employing the Coleman-Gurtin heat conduction, establishing a decay rate of type $t^{-4}$. Next, we demonstrate exponential stability in the case when Gurtin-Pipkin heat conduction is applied.

[23] 2311.16305

On variable-order fractional linear viscoelasticity

We discuss a generalisation of fractional linear viscoelasticity based on Scarpi's approach to variable-order fractional calculus. After reviewing the general mathematical framework, we introduce the variable-order fractional Maxwell model as a simple example for our analysis. We then provide some physical considerations for the fractionalisation procedure and on the choice of the transition functions. Lastly, we compute the material functions for the considered model and evaluate them numerically for exponential-type and Mittag-Leffler-type order functions.

[24] 2311.16307

Orientable total domination in graphs

Given a directed graph $D$, a set $S \subseteq V(D)$ is a total dominating set of $D$ if each vertex in $D$ has an in-neighbor in $S$. The total domination number of $D$, denoted $\gamma_t(D)$, is the minimum cardinality among all total dominating sets of $D$. Given an undirected graph $G$, we study the maximum and minimum total domination numbers among all orientations of $G$. That is, we study the upper (or lower) orientable domination number of $G$, $\rm{DOM}_t(G)$ (or $\rm{dom}_t(G)$), which is the largest (or smallest) total domination number over all orientations of $G$. We characterize those graphs with $\rm{DOM}_t(G) =\rm{dom}_t(G)$ when the girth is at least $7$ as well as those graphs with $\rm{dom}_t(G) = |V(G)|-1$. We also consider how these parameters are effected by removing a vertex from $G$, give exact values of $\rm{DOM}_t(K_{m,n})$ and $\rm{dom}_t(K_{m,n})$ and bound these parameters when $G$ is a grid graph.

[25] 2311.16310

Strict Frechet and generalized differentiability of the metric projection operator onto balls in Hilbert spaces

In this paper, we prove strict Frechet differentiability of the metric projection operator onto closed balls in Hilbert spaces, and we find exact expressions for Frechet derivatives. Since Frechet differentiability implies Gateaux directional differentiability, the results obtained in this paper strengthens the results in [8] and [10] about the directional differentiability of the metric projection operator onto closed balls in Hilbert spaces. We apply the Frechet differentiability of the metric projection onto closed balls in Hilbert spaces to study the generalized differentiability of the metric projection operator.

[26] 2311.16322

Interaction homotopy and interaction homology

Interactions in complex systems are widely observed across various fields, drawing increased attention from researchers. In mathematics, efforts are made to develop various theories and methods for studying the interactions between spaces. In this work, we present an algebraic topology framework to explore interactions between spaces. We introduce the concept of interaction spaces and investigate their homotopy, singular homology, and simplicial homology. Furthermore, we demonstrate that interaction singular homology serves as an invariant under interaction homotopy. We believe that the proposed framework holds potential for practical applications.

[27] 2311.16325

Darboux transformations and the algebra $\mathcal{D}(W)$

The problem of finding weight matrices $W(x)$ of size $N \times N$ such that the associated sequence of matrix-valued orthogonal polynomials are eigenfunctions of a second-order matrix differential operator is known as the Matrix Bochner Problem. This paper aims to study Darboux transformations between these weight matrices and to establish a direct connection with the structure of the algebra $\mathcal D(W)$. We find several general properties and provide an explicit description of the Darboux equivalence classes for scalar classical weights. Additionally, we determine the algebra $\mathcal{D}(W)$ when $W$ is a direct sum of classical scalar weights.

[28] 2311.16327

A Hodge filtration on chiral homology and Poisson homology of associated schemes

We introduce filtrations in chiral homology complexes of smooth elliptic curves, exploiting the mixed Hodge structure on cohomology groups of configuration spaces. We use these to relate the chiral homology of a smooth elliptic curve with coefficients in a vertex algebra with the Poisson homology of the associated Poisson scheme. As an application we deduce finite dimensionality results for chiral homology in low degrees.

[29] 2311.16332

Statistical Proper Orthogonal Decomposition for model reduction in feedback control

Feedback control synthesis for nonlinear, parameter-dependent fluid flow control problems is considered. The optimal feedback law requires the solution of the Hamilton-Jacobi-Bellman (HJB) PDE suffering the curse of dimensionality. This is mitigated by Model Order Reduction (MOR) techniques, where the system is projected onto a lower-dimensional subspace, over which the feedback synthesis becomes feasible. However, existing MOR methods assume at least one relaxation of generality, that is, the system should be linear, or stable, or deterministic. We propose a MOR method called Statistical POD (SPOD), which is inspired by the Proper Orthogonal Decomposition (POD), but extends to more general systems. Random samples of the original dynamical system are drawn, treating time and initial condition as random variables similarly to possible parameters in the model, and employing a stabilizing closed-loop control. The reduced subspace is chosen to minimize the empirical risk, which is shown to estimate the expected risk of the MOR solution with respect to the distribution of all possible outcomes of the controlled system. This reduced model is then used to compute a surrogate of the feedback control function in the Tensor Train (TT) format that is computationally fast to evaluate online. Using unstable Burgers' and Navier-Stokes equations, it is shown that the SPOD control is more accurate than Linear Quadratic Regulator or optimal control derived from a model reduced onto the standard POD basis, and faster than the direct optimal control of the original system.

[30] 2311.16340

New definitions in the theory of Type 1 computable topological spaces

Motivated by the two remarks, that the study of computability based on the use of numberings -- Type 1 computability -- does not have to be restricted to countable sets equipped with onto numberings, and that computable topologies have been in part developed with the implicit hypothesis that the considered spaces should be computably separable, we propose new definitions for Type 1 computable topological spaces. We define computable topological spaces without making reference to a basis. Following Spreen, we show that the use of a formal inclusion relation should be systematized, and that it cannot be avoided if we want computable topological spaces to generalize computable metric spaces. We also compare different notions of effective bases. The first one, introduced by Nogina, is based on an effective version of the statement "a set $O$ is open if for any point in $O$, there is a basic set containing that point and contained in $O$''. The second one, associated to Lacombe, is based on an effective version of "a set $O$ is open if it can be written as a union of basic open sets''. We show that neither of these notions of basis is completely satisfactory: Nogina bases do not permit to define computable topologies unless we restrict our attention to countable sets, and the conditions associated to Lacombe bases are too restrictive, and they do not apply to metric spaces unless we add effective separability hypotheses. We define a new notion of basis, based on an effective version of the Nogina statement, but adding to it several classically empty conditions, expressed in terms of formal inclusion relations. Finally, we obtain a new version of the theorem of Moschovakis which states that the Lacombe and Nogina approaches coincide on countable recursive Polish spaces, but which applies to sets equipped with non-onto numberings, and with effective separability as a sole hypothesis.

[31] 2311.16341

Domination of nonlinear semigroups generated by regular, local Dirichlet forms

In this article we study perturbations of local, nonlinear Dirichlet forms on arbitrary topological measure spaces. We show that the semigroup of a local Dirichlet form \(\mathcal{E}\) dominates the semigroup generated by another functional \(\mathcal{F}\) if, and only if, \(\mathcal{F}\) is a specific zero order perturbation of \(\mathcal{E}\). This helps to classify the perturbations that lie between Neumann and Dirichlet boundary conditions.

[32] 2311.16350

Early warning signs of critical transitions -- The $α$-stable case

Statistical early warning signs can be used to identify an approaching bifurcation in stochastic dynamical systems and are now regularly employed in applications concerned with the identification of potential rapid, non-linear change or tipping points. However, the reliability of these early warning signs relies on a number of key mathematical assumptions, most notably the presence of Gaussian noise. We here show that for systems driven by non-Gaussian, $\alpha$-stable noise, the classical early warning signs of rising variance and autocorrelation are not supported by mathematical theory and their use poses the danger of spurious, false-positive results. To address this, we provide a generalized approach by introduce the scaling factor $\gamma_X$ as an alternative early warning sign. We show that in the case of the Ornstein-Uhlenbeck process, there exists a direct inverse relationship between $\gamma_{X}$ and the bifurcation parameter, telling us that $\gamma_{X}$ will increase as we approach the bifurcation. Our numerical simulations confirm theoretical results and show that our findings generalize well to non-linear, non-equilibrium systems. We thus provide a generalized, robust and applicable statistical early warning sign for systems driven by Gaussian and non-Gaussian $\alpha$-stable noise.

[33] 2311.16355

Elementary axioms for parts in toposes

Elementary extensions to the topos axioms are considered to describe connectedness, which further help complete a synthetic way of describing precohesiveness over the full subcategory of objects with decidable equality. In this setting, a sufficiently powerful metatheory provides a complete axiomatic description for precohesion over a boolean topos.

[34] 2311.16358

Counting sign changes of partial sums of random multiplicative functions

Let $f$ be a Rademacher random multiplicative function. Let $$M_f(u):=\sum_{n \leq u} f(n)$$ be the partial sum of $f$. Let $V_f(x)$ denote the number of sign changes of $M_f(u)$ up to $x$. We show that for any constant $c > 2$, $$V_f(x) = \Omega ((\log \log \log x)^{1/c} )$$ almost surely.

[35] 2311.16367

Regularized Reduced Order Lippman-Schwinger-Lanczos Method for Inverse Scattering Problems in the Frequency Domain

Inverse scattering has a broad applicability in quantum mechanics, remote sensing, geophysical, and medical imaging. This paper presents a robust direct reduced order model (ROM) method for solving inverse scattering problems based on an efficient approximation of the resolvent operator regularizing the Lippmann-Schwinger-Lanczos (LSL) algorithm. We show that the efficiency of the method relies upon the weak dependence of the orthogonalized basis on the unknown potential in the Schr\"odinger equation by demonstrating that the Lanczos orthogonalization is equivalent to performing Gram-Schmidt on the ROM time snapshots. We then develop the LSL algorithm in the frequency domain with two levels of regularization. We show that the same procedure can be extended beyond the Schr\"odinger formulation to the Helmholtz equation, e.g., to imaging the conductivity using diffusive electromagnetic fields in conductive media with localized positive conductivity perturbations. Numerical experiments for Helmholtz and Schr\"odinger problems show that the proposed bi-level regularization scheme significantly improves the performance of the LSL algorithm, allowing for good reconstructions with noisy data and large data sets.

[36] 2311.16369

Advances in the equivariant minimal model program and their applications in complex and arithmetic dynamics

This note reports some advances in the Equivariant Minimal Model Program (EMMP) for non-isomorphic surjective endomorphisms and their applications in complex and arithmetic dynamics.

[37] 2311.16371

Omega theorems for logarithmic derivatives of zeta and $L$-functions

We establish several new $\Omega$-theorems for logarithmic derivatives of the Riemann zeta function and Dirichlet $L$-functions. In particular, this improves on earlier work of Landau (1911), Bohr-Landau (1913), and recent work of Lamzouri.

[38] 2311.16373

Twisted super Yangians of type AIII and their representations

We study the super analogue of the Molev-Ragoucy reflection algebras, which we call twisted super Yangians of type AIII, and classify their finite-dimensional irreducible representations. These superalgebras are coideal subalgebras of the super Yangian $\mathscr{Y}(\mathfrak{gl}_{m|n})$ and are associated with symmetric pairs of type AIII in Cartan's classification. We establish the Schur-Weyl type duality between degenerate affine Hecke algebras of type BC and twisted super Yangians.

[39] 2311.16379

Enhanced the Fast Fractional Fourier Transform (FRFT) scheme using the closed Newton-Cotes rules

The paper considers the fractional Fourier transform (FRFT)--based numerical inversion of Fourier and Laplace transforms and the closed Newton Cotes quadrature rules. It is shown that the fast FRFT of a QN-long weighted sequence is the composite of two fast FRFTs: the fast FRFT of a Q-long weighted sequence and the fast FRFT of an N-long sequence. The Newton-Cotes rules, the composite fast FRFT, and non-weighted fast Fractional Fourier transform (FRFT) algorithms are applied to the Variance Gamma distribution and the Generalized Tempered Stable (GTS) distribution for illustrations. Compared to the non-weighted fast FRFT, the composite fast FRFT provides more accurate results with a small sample size, and the accuracy increases with the number of weights (Q).

[40] 2311.16382

On indication, strict monotonicity, and efficiency of projections in a general class of path-based data envelopment models

Data envelopment analysis (DEA) theory formulates a number of desirable properties that DEA models should satisfy. Among these, indication, strict monotonicity, and strong efficiency of projections tend to be grouped together in the sense that, in individual models, typically, either all three are satisfied or all three fail at the same time. Specifically, in slacks-based graph models, the three properties are always met; in path-based models, such as radial models, directional distance function models, and the hyperbolic function model, the three properties, with some minor exceptions, typically all fail. Motivated by this observation, the article examines relationships among indication, strict monotonicity, and strong efficiency of projections in the class of path-based models over variable returns-to-scale technology sets. Under mild assumptions, it is shown that the property of strict monotonicity and strong efficiency of projections are equivalent, and that both properties imply indication. This paper also characterises a narrow class of technology sets and path directions for which the three properties hold in path-based models.

[41] 2311.16389

Quantitative PL bordism

We study PL bordism theories from a quantitative perspective. Such theories include those of PL manifolds, ordinary homology theory, as well as various more exotic theories such as bordism of Witt spaces. In all these cases we show that a null-bordant cycle of bounded geometry and $V$ simplices has a filling of bounded geometry whose number of simplices is slightly superlinear in $V$. This bound is similar to that found in our previous work on smooth cobordism.

[42] 2311.16390

Relative Fractional Packing Number and Its Properties

The concept of the \textit{relative fractional packing number} between two graphs $G$ and $H$, initially introduced in arXiv:2307.06155 [math.CO], serves as an upper bound for the ratio of the zero-error Shannon capacity of these graphs. Defined as: \begin{equation*} \sup\limits_{W} \frac{\alpha(G \boxtimes W)}{\alpha(H \boxtimes W)} \end{equation*} where the supremum is computed over all arbitrary graphs and $\boxtimes$ denotes the strong product of graphs. This article delves into various critical theorems regarding the computation of this number. Specifically, we address its NP-hardness and the complexity of approximating it. Furthermore, we develop a conjecture for necessary and sufficient conditions for this number to be less than one. We also validate this conjecture for specific graph families. Additionally, we present miscellaneous concepts and introduce a generalized version of the independence number that gives insights that could significantly contribute to the study of the relative fractional packing number.

[43] 2311.16395

Cyclic complementary extensions and skew-morphisms

A cyclic complementary extension of a finite group $A$ is a finite group $G$ which contains $A$ and a cyclic subgroup $C$ such that $A\cap C=\{1_G\}$ and $G=AC$. For any fixed generator $c$ of the cyclic factor $C=\langle c\rangle$ of order $n$ in a cyclic complementary extension $G=AC$, the equations $cx=\varphi(x)c^{\Pi(x)}$, $x\in A$, determine a permutation $\varphi:A\to A$ and a function $\Pi:A\to\mathbb{Z}_n$ on $A$ characterized by the properties: (a) $\varphi(1_A)=1_A$ and $\Pi(1_A)\equiv1\pmod{n}$; (b) $\varphi(xy)=\varphi(x)\varphi^{\Pi(x)}(y)$ and $\Pi(xy)\equiv\sum_{i=1}^{\Pi(x)}\Pi(\varphi^{i-1}(y))\pmod{n}$, for all $x,y\in A$. The permutation $\varphi$ is called a skew-morphism of $A$ and has already been extensively studied. One of the main contributions of the present paper is the recognition of the importance of the function $\Pi$, which we call the extended power function associated with $\varphi$. We show that {\em every} cyclic complementary extension of $A$ is determined and can be constructed from a skew-morphism $\varphi$ of $A$ and an extended power function $\Pi$ associated with $\varphi$. As an application, we present a classification of cyclic complementary extensions of cyclic groups obtained using skew-morphisms which are group automorphisms.

[44] 2311.16398

Periodic homogenisation for $P(φ)_2$

We consider the periodic homogenisation problem for dynamical $P(\phi)_2$, a toy model that combines both renormalisation in singular stochastic PDEs and homogenisation. Our result shows that the two limiting procedures commute in this case.

[45] 2311.16399

Decentralized Douglas-Rachford splitting methods for smooth optimization over compact submanifolds

We study decentralized smooth optimization problems over compact submanifolds. Recasting it as a composite optimization problem, we propose a decentralized Douglas-Rachford splitting algorithm, DDRS. When the proximal operator of the local loss function does not have a closed-form solution, an inexact version of DDRS, iDDRS, is also presented. Both algorithms rely on an ingenious integration of the nonconvex Douglas-Rachford splitting algorithm with gradient tracking and manifold optimization. We show that our DDRS and iDDRS achieve the best-known convergence rate of $\mathcal{O}(1/K)$. The main challenge in the proof is how to handle the nonconvexity of the manifold constraint. To address this issue, we utilize the concept of proximal smoothness for compact submanifolds. This ensures that the projection onto the submanifold exhibits convexity-like properties, which allows us to control the consensus error across agents. Numerical experiments on the principal component analysis are conducted to demonstrate the effectiveness of our decentralized DRS compared with the state-of-the-art ones.

[46] 2311.16403

Towards the classification of finite-dimensional diagonally graded commutative algebras

Any finite-dimensional commutative (associative) graded algebra with all nonzero homogeneous subspaces one-dimensional is defined by a symmetric coefficient matrix. This algebraic structure gives a basic kind of $A$-graded algebras originally studied by Arnold. In this paper, we call them diagonally graded commutative algebras (DGCAs) and verify that the isomorphism classes of DGCAs of dimension $\leq 7$ over an arbitrary field are in bijection with the equivalence classes consisting of coefficient matrices with the same distribution of nonzero entries, while dramatically there may be infinitely many isomorphism classes of dimension $n$ corresponding to one equivalence class of coefficient matrices when $n\geq 8$. Furthermore, we adopt the Skjelbred-Sund method of central extensions to study the isomorphism classes of DGCAs, and associate any DGCA with a undirected simple graph to explicitly describe its corresponding second (graded) commutative cohomology group as an affine variety.

[47] 2311.16407

$1$-stable fluctuation of the derivative martingale of branching random walk

In this paper, we study the functional convergence in law of the fluctuations of the derivative martingale of branching random walk on the real line. Our main result strengthens the results of Buraczewski et. al. [Ann. Probab., 2021] and is the branching random walk counterpart of the main result of Maillard and Pain [Ann. Probab., 2019] for branching Brownian motion.

[48] 2311.16410

Reduced-order modeling for parameterized PDEs via implicit neural representations

We present a new data-driven reduced-order modeling approach to efficiently solve parametrized partial differential equations (PDEs) for many-query problems. This work is inspired by the concept of implicit neural representation (INR), which models physics signals in a continuous manner and independent of spatial/temporal discretization. The proposed framework encodes PDE and utilizes a parametrized neural ODE (PNODE) to learn latent dynamics characterized by multiple PDE parameters. PNODE can be inferred by a hypernetwork to reduce the potential difficulties in learning PNODE due to a complex multilayer perceptron (MLP). The framework uses an INR to decode the latent dynamics and reconstruct accurate PDE solutions. Further, a physics-informed loss is also introduced to correct the prediction of unseen parameter instances. Incorporating the physics-informed loss also enables the model to be fine-tuned in an unsupervised manner on unseen PDE parameters. A numerical experiment is performed on a two-dimensional Burgers equation with a large variation of PDE parameters. We evaluate the proposed method at a large Reynolds number and obtain up to speedup of O(10^3) and ~1% relative error to the ground truth values.

[49] 2311.16418

Curves and Length

This is a systematic accounting of the classical theorems of Jordan and Tonelli, as well as an introduction to the theory of the Weierstrass integral which in its definitive form is due to Cesari. This is installment II of a four part discussion of certain aspects of Real Analysis: Functions of a Single Variable, Curves and Length, Functions of Several Variables, and Surfaces and Area.

[50] 2311.16427

Finite-Time Computation of Polyhedral Input-Saturated Output-Admissible Sets

The paper introduces a novel algorithm for computing the output admissible set of linear discrete-time systems subject to input saturation. The proposed method takes advantage of the piecewise-affine dynamics to propagate the output constraints within the non-saturated and saturated regions. The constraints are then shared between regions to ensure a proper transition from one region to another. The resulting algorithm generates a set that is proven to be polyhedral, safe, positively invariant, and finitely determined. Moreover, the set is also proven to be strictly larger than the maximal output admissible set that would be obtained by treating input saturation as a constraint.

[51] 2311.16428

Jerison-Lee identity and Semi-linear subelliptic equation on CR manifold

Motivated by Jerison-Lee identities in Cauchy-Riemann(CR) manifold on subelliptic equations, several new types of identities on CR manifold are found with the help of dimensional conservation and invariant tensors. These identities are used to get the rigidity result for a class of CR Lane-Emden equation in subcritical case, where rigidity means that the subelliptic equation has no other solution than some constant at least when parameters are in a certain range. The rigidity result also deduces the sharp Folland-Stein inequality on closed CR manifold. The theoretical framework for finding identities is also established, which answers the question raised up by Jerison-Lee.

[52] 2311.16435

Unique determination by a single far-field measurement for an inverse elastic problem

This paper is concerned with the unique identification of the shape of a scatterer through a single far-field pattern in an inverse elastic medium scattering problem with a generalized transmission boundary condition. The uniqueness issue by a single far-field measurement is a challenging problem in inverse scattering theory, which has a long and colorful history. In this paper, we establish the uniqueness results by a single far-field measurement under a generic scenario when dealing with underlying elastic scatterers exhibiting polygonal-nest or polygonal-cell structures. Furthermore, for polygonal-nest or polygonal-cell structure scatterers associated with density and boundary impedance parameters as piecewise constants, we show that these physical quantities can be uniquely determined simultaneously by a single far-field measurement. The corresponding proof relies heavily on examining the singular behaviour of a coupled PDE system near a corner in a microlocal manner.

[53] 2311.16437

Groups which are metrically LEF

We consider metric versions of the notions of local embeddability and LEF. We pay special attention to normally finitely generated groups with word metrics.

[54] 2311.16438

The structure of the wave operators in four dimensions in the presence of resonances

We show that the wave operators for Schr\"{o}dinger scattering in $\mathbb{R}^4$ have a particular form which depends on the existence of resonances. As a consequence of this form, we determine the contribution of resonances to the index of the wave operator.

[55] 2311.16454

An hp-Adaptive Sampling Algorithm on Dispersion Relation Reconstruction for 2D Photonic Crystals

Computing the dispersion relation for two-dimensional photonic crystals is a notoriously challenging task: It involves solving parameterized Helmholtz eigenvalue problems with high-contrast coefficients. To resolve the challenge, we propose a novel hp-adaptive sampling scheme that can detect singular points via adaptive mesh refinement in the parameter domain, and meanwhile, allow for adaptively enriching the local polynomial spaces on the elements that do not contain singular points. In this way, we obtain an element-wise interpolation on an adaptive mesh. We derive an exponential convergence rate when the number of singular points is finite, and a first-order convergence rate otherwise. Numerical tests are provided to illustrate its performance.

[56] 2311.16486

On the adaptation of causal forests to manifold data

Researchers often hold the belief that random forests are "the cure to the world's ills" (Bickel, 2010). But how exactly do they achieve this? Focused on the recently introduced causal forests (Athey and Imbens, 2016; Wager and Athey, 2018), this manuscript aims to contribute to an ongoing research trend towards answering this question, proving that causal forests can adapt to the unknown covariate manifold structure. In particular, our analysis shows that a causal forest estimator can achieve the optimal rate of convergence for estimating the conditional average treatment effect, with the covariate dimension automatically replaced by the manifold dimension. These findings align with analogous observations in the realm of deep learning and resonate with the insights presented in Peter Bickel's 2004 Rietz lecture.

[57] 2311.16546

Phase transitions for the $XY$ model in non-uniformly elliptic and Poisson-Voronoi environments

The goal of this paper is to analyze how the celebrated phase transitions of the $XY$ model are affected by the presence of a non-elliptic quenched disorder. In dimension $d=2$, we prove that if one considers an $XY$ model on the infinite cluster of a supercritical percolation configuration, the Berezinskii-Kosterlitz-Thouless (BKT) phase transition still occurs despite the presence of quenched disorder. The proof works for all $p>p_c$ (site or edge). We also show that the $XY$ model defined on a planar Poisson-Voronoi graph also undergoes a BKT phase transition. When $d\geq 3$, we show in a similar fashion that the continuous symmetry breaking of the $XY$ model at low enough temperature is not affected by the presence of quenched disorder such as supercritical percolation (in $\mathbb{Z}^d$) or Poisson-Voronoi (in $\mathbb{R}^d$). Adapting either Fr\"{o}hlich-Spencer's proof of existence of a BKT phase transition or the more recent proofs of Lammers, van Engelenburg-Lis and Aizenman-Harel-Peled-Shapiro to such non-uniformly elliptic disorders appears to be non-trivial. Instead, our proofs rely on a relatively little known correlation inequality called Wells' inequality.

[58] 2311.16547

Existence and non-existence results to a mixed Schrodinger system in a plane

This article focuses on the existence and non-existence of solutions for the following system of local and nonlocal type \begin{equation*} \left\{ \begin{aligned} -\partial_{xx}u + (-\Delta)_{y}^{s_{1}} u + u - u^{2_{s_{1}}^{}-1} = \kappa \alpha h(x,y) u^{\alpha-1}v^{\beta} & \quad \mbox{in} ~ \mathbb{R}^{2}, -\partial_{xx}v + (-\Delta)_{y}^{s_{2}} v + v- v^{2_{s_{2}}^{}-1} = \kappa \beta h(x,y) u^{\alpha}v^{\beta-1} & \quad \mbox{in} ~ \mathbb{R}^{2}, u,v ~ \geq ~0 \quad \mbox{in} ~ \mathbb{R}^{2}, \end{aligned} \right. \end{equation*} where $s_{1},s_{2} \in (0,1),~\alpha,\beta>1,~\alpha+\beta \leq \min \{ 2_{s_{1}}^{},2_{s_{2}}^{}\}$, and $2_{s_i}^{} = \frac{2(1+s_i)}{1-s_i}, i=1,2$. The existence of a ground state solution entirely depends on the behaviour of the parameter $\kappa>0$ and on the function $h$. In this article, we prove that a ground state solution exists in the subcritical case if $\kappa$ is large enough and $h$ satisfies (1.3). Further, if $\kappa$ becomes very small in this case then there does not exist any solution to our system. The study in the critical case, i.e. $s_1=s_2=s, \alpha+\beta=2_s$, is more complex and the solution exists only for large $\kappa$ and radial $h$ satisfying (H1). Finally, we establish a Pohozaev identity which enables us to prove the non-existence results under some smooth assumptions on $h$.

[59] 2311.16558

Remarks on SHD spaces and more divergence properties

The class of SHD spaces was recently introduced in [12]. The first part of this paper focuses on answering most of the questions presented in that article. For instance, we exhibit an example of a non-SHD Tychonoff space $X$ such that $\mathscr{F}[X]$, the Pixley-Roy hyperspace of $X$, $\beta X$, the Stone-\v{C}ech compactification of $X$, and $C_p(X)$, the ring of continuous functions over $X$ equipped with the topology of pointwise convergence, are SHD. In the second part of this work we will present some variations of the SHD notion, namely, the WSHD property and the OHD property. Furthermore, we will pay special attention to the relationships between $X$ and $\mathscr{F}[X]$ regarding these new concepts.

[60] 2311.16559

Graph Partitioning with Fujitsu Digital Annealer

Graph partitioning, or community detection, is the cornerstone of many fields, such as logistics, transportation and smart power grids. Efficient computation and efficacious evaluation of communities are both essential, especially in commercial and industrial settings. However, the solution space of graph partitioning increases drastically with the number of vertices and subgroups. With an eye to solving large scale graph partitioning and other optimization problems within a short period of time, the Digital Annealer (DA), a specialized CMOS hardware also featuring improved algorithms, has been devised by Fujitsu Ltd. This study gauges Fujitsu DA's performance and running times. The modularity was implemented as both the objective function and metric for the solutions. The graph partitioning problems were formatted into Quadratic Unconstrained Binary Optimization (QUBO) structures so that they could be adequately imported into the DA. The DA yielded the highest modularity among other studies when partitioning Karate Club, Les Miserables, American Football, and Dolphin. Moreover, the DA was able to partition the Case 1354pegase power grid network into 45 subgroups, calling for 60,930 binary variables, whilst delivering optimal modularity results within a solving time of roughly 80 seconds. Our results suggest that the Fujitsu DA can be applied for rapid and efficient optimization for graph partitioning.

[61] 2311.16562

Parameterized Complexity of Factorization Problems

We study the parameterized complexity of the following factorization problem: given elements $a,a_1, \ldots, a_m$ of a monoid and a parameter $k$, can $a$ be written as the product of at most (or exactly) $k$ elements from $a_1, \ldots, a_m$. Several new upper bounds and fpt-equivalences with more restricted problems (subset sum and knapsack) are shown. Finally, some new upper bounds for variants of the parameterized change-making problems are shown.

[62] 2311.16568

Active RIS Enhanced Spectrum Sensing for Cognitive Radio Networks

In opportunistic cognitive radio networks, when the primary signal is very weak compared to the background noise, the secondary user requires long sensing time to achieve a reliable spectrum sensing performance, leading to little remaining time for the secondary transmission. To tackle this issue, we propose an active reconfigurable intelligent surface (RIS) assisted spectrum sensing system, where the received signal strength from the interested primary user can be enhanced and underlying interference within the background noise can be mitigated as well. In comparison with the passive RIS, the active RIS can not only adapt the phase shift of each reflecting element but also amplify the incident signals. Notably, we study the reflecting coefficient matrix (RCM) optimization problem to improve the detection probability given a maximum tolerable false alarm probability and limited sensing time. Then, we show that the formulated problem can be equivalently transformed to a weighted mean square error minimization problem using the principle of the well-known weighted minimum mean square error (WMMSE) algorithm, and an iterative optimization approach is proposed to obtain the optimal RCM. In addition, to fairly compare passive RIS and active RIS, we study the required power budget of the RIS to achieve a target detection probability under a special case where the direct links are neglected and the RIS-related channels are line-of-sight. Via extensive simulations, the effectiveness of the WMMSE-based RCM optimization approach is demonstrated. Furthermore, the results reveal that the active RIS can outperform the passive RIS when the underlying interference within the background noise is relatively weak, whereas the passive RIS performs better in strong interference scenarios because the same power budget can support a vast number of passive reflecting elements for interference mitigation.

[63] 2311.16573

Small mass uniqueness in the anisotropic liquid drop model and the critical mass problem

Small mass uniqueness in the anisotropic atomic liquid drop model for all values of the parameters is obtained and the critical mass conjecture is investigated.

[64] 2311.16574

Homogenization of nonlocal convolution type operators: Approximation for the resolvent with corrector

In $L_2(\mathbb{R}^d)$, we consider a selfadjoint bounded operator ${\mathbb A}_\varepsilon$, $\varepsilon >0$, of the form $$ ({\mathbb A}_\varepsilon u) (\mathbf{x}) = \varepsilon^{-d-2} \int_{\mathbb{R}^d} a((\mathbf{x} - \mathbf{y} )/ \varepsilon ) \mu(\mathbf{x} /\varepsilon, \mathbf{y} /\varepsilon) \left( u(\mathbf{x}) - u(\mathbf{y}) \right)\, d\mathbf{y}. $$ It is assumed that $a(\mathbf{x})$ is a nonnegative function of class $L_1(\mathbb{R}^d)$ such that \hbox{$a(-\mathbf{x}) = a(\mathbf{x})$} and $\mu(\mathbf{x},\mathbf{y})$ is $\mathbb{Z}^d$-periodic in each variable and such that $\mu(\mathbf{x},\mathbf{y}) = \mu(\mathbf{y},\mathbf{x})$ and $0< \mu_- \leqslant \mu(\mathbf{x},\mathbf{y}) \leqslant \mu_+< \infty$. Moreover, it is assumed that the moments $M_k (a)= \int_{\mathbb{R}^d} | \mathbf{x} |^k a(\mathbf{x})\,d\mathbf{x}$, $k=1,2,3,4,$ are finite. We obtain approximation of the resolvent $({\mathbb A}_\varepsilon + I)^{-1}$ for small $\varepsilon$ in the operator norm on $L_2(\mathbb{R}^d)$ with error of order $O(\varepsilon^2)$.

[65] 2311.16578

Counting 7-Arcs in Projective Planes over Finite Fields

Given a collection of points in the plane, classifying which subsets are collinear is a natural problem and is related to classical geometric constructions. We consider collections of points in a projective plane over a finite field such that no three are collinear. This is a finite set and its size is both combinatorially interesting and has deeper topological consequences. We count the number of such collections classified by the algebraic symmetries of the finite field. Variations of this problem have been considered by Glynn, Bergvall, Das, O'Connor et al. We obtain the counts for 7 points over fields of characteristic 2. These new counts are governed by the existence and classification of a configuration of points called the Fano plane.

[66] 2311.16583

The Inverse of the Complex Gamma Function

We consider the functional inverse of the Gamma function in the complex plane, where it is multi-valued, and define a set of suitable branches by proposing a natural extension from the real case.

[67] 2311.16591

Degenerate drift-diffusion systems for memristors

A system of degenerate drift-diffusion equations for the electron, hole, and oxygen vacancy densities, coupled to the Poisson equation for the electric potential, is analyzed in a three-dimensional bounded domain with mixed Dirichlet-Neumann boundary conditions. The equations model the dynamics of the charge carriers in a memristor device in the high-density regime. Memristors can be seen as nonlinear resistors with memory, mimicking the conductance response of biological synapses. The global existence of weak solutions and the weak-strong uniqueness property is proved. Thanks to the degenerate diffusion, better regularity results compared to linear diffusion can be shown, in particular the boundedness of the solutions.

[68] 2311.16596

Continued fractions of cubic irrationalities

We highlight some facts about continued fractions of real cubic irrationalities. This may be thought as a small section in a textbook on continued fractions.

[69] 2311.16597

Relative Calabi-Yau structures and perverse schobers on surfaces

We discuss relative Calabi-Yau structures on functors between $R$-linear stable $\infty$-categories, with $R$ any $\mathbb{E}_\infty$-ring spectrum, generalizing previous treatments in the setting of dg-categories. Using their gluing properties, we furthermore construct relative Calabi-Yau structures on the global sections of perverse schobers, i.e. categorified perverse sheaves, on surfaces with boundary. We apply this to examples related to Fukaya categories and representation theory.

[70] 2311.16598

Rectangular Hull Confidence Regions for Multivariate Parameters

We introduce three notions of multivariate median bias, namely, rectilinear, Tukey, and orthant median bias. Each of these median biases is zero under a suitable notion of multivariate symmetry. We study the coverage probabilities of rectangular hull of $B$ independent multivariate estimators, with special attention to the number of estimators $B$ needed to ensure a miscoverage of at most $\alpha$. It is proved that for estimators with zero orthant median bias, we need $B\geq c\log_2(d/\alpha)$ for some constant $c > 0$. Finally, we show that there exists an asymptotically valid (non-trivial) confidence region for a multivariate parameter $\theta_0$ if and only if there exists a (non-trivial) estimator with an asymptotic orthant median bias of zero.

[71] 2311.16600

Morphisms of Cuntz-Pimsner algebras from completely positive maps

We introduce positive correspondences as right C*-modules with left actions given by completely positive maps. Positive correspondences form a semi-category that contains the C*-correspondence (Enchilada) category as a "retract". Kasparov's KSGNS construction provides a semi-functor from this semi-category onto the C*-correspondence category. The need for left actions by completely positive maps appears naturally when we consider morphisms between Cuntz-Pimsner algebras, and we describe classes of examples arising from projections on C*-correspondences and Fock spaces, as well as examples from conjugation by bi-Hilbertian bimodules of finite index.

[72] 2311.16606

A note on extreme points of the unit of Hardy-Lorentz spaces

We show that inner functions are extreme points of the unit ball of the Hardy-Lorentz space $H(\Lambda(\varphi))$, for $\Lambda(\varphi)$ a Lorentz space with $\varphi$ strictly increasing and strictly concave.

[73] 2311.16608

Fourier Features for Identifying Differential Equations (FourierIdent)

We investigate the benefits and challenges of utilizing the frequency information in differential equation identification. Solving differential equations and Fourier analysis are closely related, yet there is limited work in exploring this connection in the identification of differential equations. Given a single realization of the differential equation perturbed by noise, we aim to identify the underlying differential equation governed by a linear combination of linear and nonlinear differential and polynomial terms in the frequency domain. This is challenging due to large magnitudes and sensitivity to noise. We introduce a Fourier feature denoising, and define the meaningful data region and the core regions of features to reduce the effect of noise in the frequency domain. We use Subspace Pursuit on the core region of the time derivative feature, and introduce a group trimming step to refine the support. We further introduce a new energy based on the core regions of features for coefficient identification. Utilizing the core regions of features serves two critical purposes: eliminating the low-response regions dominated by noise, and enhancing the accuracy in coefficient identification. The proposed method is tested on various differential equations with linear, nonlinear, and high-order derivative feature terms. Our results demonstrate the advantages of the proposed method, particularly on complex and highly corrupted datasets.

[74] 2311.16609

Eigenmatrix for unstructured sparse recovery

This paper considers the unstructured sparse recovery problems in a general form. Examples include rational approximation, spectral function estimation, Fourier inversion, Laplace inversion, and sparse deconvolution. The main challenges are the noise in the sample values and the unstructured nature of the sample locations. This paper proposes the eigenmatrix, a data-driven construction with desired approximate eigenvalues and eigenvectors. The eigenmatrix offers a new way for these sparse recovery problems. Numerical results are provided to demonstrate the efficiency of the proposed method.

[75] 2311.16611

Numerical Method for a Controlled Sweeping Process with Nonsmooth Sweeping Set

The numerical method developed in [30] for optimal control problems involving sweeping processes with smooth sweeping set C is generalized to the case where C is nonsmooth, namely, C is the intersection of a finite number of sublevel sets of smooth functions. The novelty of this extension resides in producing for the general setting a different approach, since the one used for the smooth sweeping sets is not applicable here.

[76] 2311.16617

Local model theory for non-generic tame potentially Barsotti--Tate deformation rings

We develop a local model theory for moduli stacks of $2$-dimensional non-scalar tame potentially Barsotti--Tate Galois representations of the Galois group of an unramified extension of $\mathbb{Q}_p$. We derive from this explicit presentations of potentially Barsotti--Tate deformation rings, allowing us to prove structural results about them, and prove various conjectures formulated by Caruso--David--M\'ezard.

[77] 2311.16619

Ore Localisation for differential graded rings; Towards Goldie's theorem for differential graded algebras

We study Ore localisation of differential graded algebras. Further we define dg-prime rings, dg-semiprime rings, and study the dg-nil radical of dg-rings. Then, we define dg-essential submodules, dg-uniform dimension, and apply all this to a dg-version of Goldie's theorem on prime dg-rings.

[78] 2311.16624

Modelisation of a rolling disk with Sympy

This paper proposes a Lagrangian approach to find the state equations of a disk rolling on a plane without friction. The approach takes advantage of a symbolic computation to simplify the reasoning.

[79] 2311.16629

Simple singularity of type $E_7$ and the complex reflection group ST34

This paper studies a family of surfaces of ${\bf C}^3$ which is a deformation of a simple singularity of type $E_7$. This family has six parameters which are regarded as basic invariants of the complex reflection group No.34 in the list of the paper of Shephard and Todd \cite{ST}. We compute 1-parameter subfamilies of the family in question corresponding to corank one reflection subgroups of No.34 group. In particular, we determine the types of simple singularities on the surfaces appeared in this manner.

[80] 2311.16631

Climbing up a random subgraph of the hypercube

Let $Q^d$ be the $d$-dimensional binary hypercube. We say that $P=\{v_1,\ldots, v_k\}$ is an increasing path of length $k-1$ in $Q^d$, if for every $i\in [k-1]$ the edge $v_iv_{i+1}$ is obtained by switching some zero coordinate in $v_i$ to a one coordinate in $v_{i+1}$. Form a random subgraph $Q^d_p$ by retaining each edge in $E(Q^d)$ independently with probability $p$. We show that there is a phase transition with respect to the length of a longest increasing path around $p=\frac{e}{d}$. Let $\alpha$ be a constant and let $p=\frac{\alpha}{d}$. When $\alphae$, whp there is a path of length $d-2$ in $Q^d_p$, and in fact, whether it is of length $d-2, d-1$, or $d$ depends on whether the all-zero and all-one vertices percolate or not.

[81] 2311.16636

On the solutions to the space-time fractional nonlinear Schrodinger equation and their dispersion

We consider the space-time fractional nonlinear Schrodinger equation. We first give a decay estimates and Holder-type estimates of the evolution operators and estimates the nonlinearity in some Sobolev spacs and Besov spaces using the harmonic tools. Then we give a priori estimates of the solution. After that we prove the local and global well-posedness of the solution and its dispersion in some significant spaces.

[82] 2311.16640

Rational numbers with small denominators in short intervals

We use bounds on bilinear forms with Kloosterman fractions and improve the error term in the asymptotic formula of Balazard and Martin (2023) on the average value of the smallest denominators of rational numbers in short intervals.

[83] 2311.16642

The homotopy decomposition of the suspension of a non-simply-connected $5$-manifold

In this paper we determine the homotopy types of the reduced suspension space of certain connected orientable closed smooth $5$-manifolds. As applications, we compute the reduced $K$-groups of $M$ and show that the suspension map between the third cohomotopy set $\pi^3(M)$ and the fourth cohomotopy set $\pi^4(\Sigma M)$ is a bijection.

[84] 2311.16643

Simplifying modular lattices by removing doubly irreducible elements

Lattices are simplified by removing some of their doubly irreducible elements, resulting in smaller lattices called racks. All vertically indecomposable modular racks of $n \le 40$ elements are listed, and the numbers of all modular lattices of $n \le 40$ elements are obtained by P\'olya counting. SageMath code is provided that allows easy access both to the listed racks, and to the modular lattices that were not listed. More than 3000-fold savings in storage space are demonstrated.

[85] 2311.16647

Analytic torsion of nilmanifolds with (2,3,5) distributions

We consider generic rank two distributions on 5-dimensional nilmanifolds, and show that the analytic torsion of their Rumin complex coincides with the Ray-Singer torsion.

[86] 2311.16649

A historical review of the Cauchy-Riemann equations and the Cauchy Theorem

In this article we take a historical tour through the Cauchy-Riemann equations and their relationship with Cauchy's theorem on the independence with respect to the path of the integral of a holomorphic function. Because of its importance we do a detailed and updated study of the contributions of d'Alembert and Euler to these topics. We also review the Cauchy works about the passage from the real to imaginary by paying attention to some arguments he uses that are not clear enough. At the end we comment briefly the evolution of Green's formula and its relation with the above problems.

[87] 2311.16659

Free groups of ideals

We study the freeness of the group $\mathrm{Inv}(D)$ of invertible ideals of an integral domain $D$, and the freeness of some related groups of (fractional) ideals. We study the relation between $\mathrm{Inv}(D)$ and $\mathrm{Inv}(D_P)$, in particular in the locally finite case, and we analyze in more detail the case where $D$ is Noetherian (obtaining a characterization of when $\mathrm{Inv}(D)$ is free for one-dimensional analytically unramified Noetherian domains) and where $D$ is Pr\"ufer.

[88] 2311.16660

Bounds on the Pythagoras number and indecomposables in biquadratic fields

We show that for all real biquadratic fields not containing $\sqrt{2}$, $\sqrt{3}$, $\sqrt{5}$, $\sqrt{6}$, $\sqrt{7},$ and $\sqrt{13}$, the Pythagoras number of the ring of algebraic integers is at least $6$. We will also provide an upper bound on the norm and the minimal (codifferent) trace of additively indecomposable integers in some families of these fields.

[89] 2311.16662

On the arithmetic of ultraproducts of commutative cancellative monoids

We develop first steps in the study of factorizations of elements in ultraproducts of commutative cancellative monoids into irreducible elements. A complete characterization of the (multi-)sets of lengths in such objects is given. As applications, we show that several important properties from factorization theory cannot be expressed as first-order statements in the language of monoids, and we construct integral domains that realize every multiset of integers larger $1$ as a multiset of lengths. Finally, we give a new proof (based on our ultraproduct techniques) of a theorem by Geroldinger, Schmid and Zhong from additive combinatorics and we propose a general method for applying ultraproducts in the setting of non-unique factorizations.

[90] 2311.16665

Recognizing trees from incomplete decks

For a given graph, the unlabeled subgraphs $G-v$ are called the cards of $G$ and the deck of $G$ is the multiset $\{G-v: v \in V(G)\}$. Wendy Myrvold [Ars Combinatoria, 1989] showed that a non-connected graph and a connected graph both on $n$ vertices have at most $\lfloor \frac{n}{2} \rfloor +1$ cards in common and she found (infinite) families of trees and non-connected forests for which this upper bound is tight. Bowler, Brown, and Fenner [Journal of Graph Theory, 2010] conjectured that this bound is tight for $n \geq 44$. In this article, we prove this conjecture for sufficiently large $n$. The main result is that a tree $T$ and a unicyclic graph $G$ on $n$ vertices have at most $\lfloor \frac{n}{2} \rfloor+1$ common cards. Combined with Myrvold's work this shows that it can be determined whether a graph on $n$ vertices is a tree from any $\lfloor \frac{n}{2}\rfloor+1$ of its cards. Based on this theorem, it follows that any forest and non-forest also have at most $\lfloor \frac{n}{2} \rfloor +1$ common cards. Moreover, we have classified all except finitely many pairs for which this bound is strict. Furthermore, the main ideas of the proof for trees are used to show that the girth of a graph on $n$ vertices can be determined based on any $\frac{2n}{3} +1$ of its cards. Lastly, we show that any $\frac{5n}{6} +2$ cards determine whether a graph is bipartite.

[91] 2311.16667

The Space of Vectored Hyperbolic Surfaces is Path-Connected

In the space $\mathcal{H}^2$ of hyperbolic surfaces decorated with a base unit vector, the topology induced by the Gromov-Hausdorff convergence coincides with the Chabauty topology on the space of discrete torsion-free subgroups of $\text{PSL}_2(\mathbb{R})$. Using paths constructed from changing the Fenchel-Nielsen coordinates and shrinking curves to cusps, we show path-connectivity of $\mathcal{H}^2$ and some of its subspaces.

[92] 2311.16690

On pyramidal groups whose number of involutions is a prime power

A Kirkman Triple System $\Gamma$ is called $m$-pyramidal if there exists a subgroup $G$ of the automorphism group of $\Gamma$ that fixes $m$ points and acts regularly on the other points. Such group $G$ admits a unique conjugacy class $C$ of involutions (elements of order $2$) and $|C|=m$. We call groups with this property $m$-pyramidal. We prove that, if $m$ is an odd prime power $p^k$, then every $m$-pyramidal group is solvable if and only if either $m=9$ or $k$ is odd. The primitive permutation groups play an important role in the proof. We also determine the orders of the $m$-pyramidal groups when $m$ is a prime number.

[93] 2311.16693

Optimal variable acceptance sampling plan for exponential distribution using Bayesian estimate under Type I hybrid censoring

In this study, variable acceptance sampling plans under Type I hybrid censoring is designed for a lot of independent and identical units with exponential lifetimes using Bayesian estimate of the parameter $\vartheta$. This approach is new from the conventional methods in acceptance sampling plan which relay on maximum likelihood estimate and minimising of Bayes risk. Bayesian estimate is obtained using squared error loss and Linex loss functions. Optimisation problem is solved for minimising the testing cost under each methods and optimal values of the plan parameters $n, t_1$ and $t_2$ are calculated. The proposed plans are illustrated using various examples and a real life case study is also conducted. Expected testing cost of the sampling plan obtained using squared error loss function is much lower than the cost of existing plans using maximum likelihood estimate.

[94] 2311.16694

On the singularities of 1-foliations in positive characteristic

We prove several theorems about 1-foliations in positive characteristic. Our main results are the following ones. (1) We show that 1-foliations on surfaces and threefolds can be resolved if one allows toric-like singularities. (2) We show that quotients by (log) canonical 1-foliations preserve the (log) singularities of the MMP. (3) We prove that quotients by multiplicative derivations preserve many properties, amongst which most F-singularities. We also formulate a notion of families of 1-foliations, and study quotients by such families.

[95] 2311.16699

An extended discontinuous Galerkin shock tracking method

In this paper, we introduce a novel high-order shock tracking method and provide a proof of concept. Our method leverages concepts from implicit shock tracking and extended discontinuous Galerkin methods, primarily designed for solving partial differential equations featuring discontinuities. To address this challenge, we solve a constrained optimization problem aiming at accurately fitting the zero iso-contour of a level set function to the discontinuities. Additionally, we discuss various robustness measures inspired by both numerical experiments and existing literature. Finally, we showcase the capabilities of our method through a series of two-dimensional problems, progressively increasing in complexity.

[96] 2311.16704

Roots and Right Factors of Polynomials and Left Eigenvalues of Matrices over Cayley-Dickson Algebras

Over a composition algebra $A$, a polynomial $f(x) \in A[x]$ has a root $\alpha$ if and only $f(x)=g(x)\cdot (x-\alpha)$ for some $g(x) \in A[x]$. We examine whether this is true for general Cayley-Dickson algebras. The conclusion is that it is when $f(x)$ is linear or monic quadratic, but false otherwise. Similar questions about the connections between $f$ and its companion $C_f(x)=f(x)\cdot \overline{f(x)}$ are studied. Finally, we compute the left eigenvalues of $2\times 2$ octonion matrices.

[97] 2311.16724

On commutators of idempotents

Let $T$ be an operator on Banach space $X$ that is similar to $- T$ via an involution $U$. Then $U$ decomposes the Banach space $X$ as $X = X_1 \oplus X_2$ with respect to which decomposition we have $U = \left(\begin{matrix} I_1 & 0 \\ 0 & -I_2 \end{matrix} \right)$, where $I_i$ is the identity operator on the closed subspace $X_i$ ($i=1, 2$). Furthermore, $T$ has necessarily the form $T = \left(\begin{matrix} 0 & * \\ * & 0 \end{matrix} \right) $ with respect to the same decomposition. In this note we consider the question when $T$ is a commutator of the idempotent $P = \left(\begin{matrix} I_1 & 0 \\ 0 & 0 \end{matrix} \right)$ and some idempotent $Q$ on $X$. We also determine which scalar multiples of unilateral shifts on $l^p$ spaces ($1 \le p \le \infty$) are commutators of idempotent operators.

[98] 2311.16729

Almost-Kähler four manifolds with harmonic self-dual Weyl curvature

We show that a compact almost-K\"ahler four manifold $(M, g, \omega)$ with harmonic self-dual Weyl curvature and constant scalar curvature is K\"ahler if $c_{1}\cdot\omega\geq 0$. We also prove an integral curvature inequality for compact almost-K\"ahler four manifolds with harmonic self-dual Weyl curvature.

[99] 2311.16731

Lyusternik-Graves Theorem for Holder Metric Regularity

The paper extends the well-known Lyusternik-Graves theorem for set-valued mappings to the Holder framework, offers an affirmative answer to an open problem proposed by Dontchev and improves recent results of He and Ng. Primal and dual necessary and sufficient conditions for Holder metric regularity are established. The results are applied to convergence analysis of a Newton-type method. Some open problems for future research are also discussed.

[100] 2311.16735

Estimates of size of cycle in a predator-prey system II

We prove estimates for the maximal and minimal predator and prey populations on the unique limit cycle in a standard predator-prey system. Our estimates are valid when the cycle exhibits small predator and prey abundances and large amplitudes. The proofs consist of constructions of several Lyapunov-type functions and derivation of a large number of non-trivial estimates, and should be of independent interest. This study generalizes results proved by the authors in (Differ Equ Dyn Syst 30, 131-159 (2022)) to a wider class of systems and, in addition, it gives simpler proofs of some already known estimates.

[101] 2311.16736

A solution of 2D incompressible Euler equation with algebraic spiral roll-up in the presence of Wiener type perturbation

Extending the results of Elling \cite{Elling-2013, Elling-2016}, we construct a weak solution of 2D incompressible Euler equation with initial vorticity of the form $w_0(x)={\left\vert x \right\vert}^{-1/\mu}g(\theta)$, where $g \in L^p(\mathbb{T})$ satisfies $\sum_{\mathbb{Z}}{\left\vert n \right\vert}^{-0.5} {\left\vert\widehat{g}(n)\right\vert} < \infty$. In particular, the solution is self-similar and shows algebraic spiral roll-up.

[102] 2311.16743

About some works of Boris Polyak on convergence of gradient methods and their development

The paper presents a review of the state-of-the-art of subgradient and accelerated methods of convex optimization, including in the presence of disturbances and access to various information about the objective function (function value, gradient, stochastic gradient, higher derivatives). For nonconvex problems, the Polak-Lojasiewicz condition is considered and a review of the main results is given. The behavior of numerical methods in the presence of sharp minima is considered. The purpose of this survey is to show the influence of the works of B.T. Polyak (1935 -- 2023) on gradient optimization methods and their neighborhoods on the modern development of numerical optimization methods.

[103] 2311.16747

A Note on the Completeness of All Translates of a Function in the Orlicz Spaces

We give a characterization of those functions whose all translates are complete in certain Orlicz space $L^{\Phi}(\mathbb{R})$. As a consequence, we identified those discrete sets $\Lambda \subseteq \mathbb{R}$ such that there exists a function in $L^{\Phi}(\mathbb{R})$ whose $\Lambda$-translates are complete. We then prove the completeness of all translates of any simple step function in other Orlicz spaces.

[104] 2311.16749

Almost-Kähler four manifolds with nonnegative biorthogonal curvature

We classify compact almost-K\"ahler four manifolds with nonnegative biorthogonal curvature.

[105] 2311.16757

Discrete Translates of an Operator in the Schatten $p$-Classes

In this manuscript, we investigate the properties of systems formed by translations of an operator in the Schatten $p$-classes $\mathcal{T}^p$. We establish the existence of Schauder frames of integer translates in $\mathcal{T}^p$ for $p>2$. Later, we provide an instance of a uniformly discrete $\Lambda \subset \mathbb{R}^{2d}$ such that there exists an operator whose $\Lambda$-translates are complete in $\mathcal{T}^p$ for all $p>1$.

[106] 2311.16765

Observations towards a proof of the Collatz conjecture using $2^{j}k+x$ number series

The document tries to put focus on sequences with certain properties and periods leading to the first value smaller than the starting value in the Collatz problem. With the idea that, if all starting numbers lead ultimately to a smaller number, all full sequences lead to 1 with a finite stopping time, the problem could be reduced to more structured shorter sequences. It is shown that this sequences exist and follow consistent rules. Potential features of an infinite cycle, also leading to a smaller number, are also discussed.

[107] 2311.16776

Thick braids and other non-trivial homotopy in configuration spaces of hard discs

We study the homotopy groups of the configuration space of discs inside a unit disc just beyond the first critical radius. We find a non-trivial `thick braid' (loop in the configuration space), which is trivial in the ordered configuration space of points when replacing each disc by its centre, in the case $n=4$. We find a non-contractible $(n-3)$-sphere for $n\ge 5$, where $r$ is between the first two critical radii, and explore the persistence of this homotopy class when the ambient unit disc is deformed. For sufficiently large $n$, we demonstrate the existence of non-trivial $\pi_k$-classes with $k

[108] 2311.16779

Affine Metric Geometry and Weak Orthogonal Groups

By following the ideas underpinning the well-established ``homogeneous model'' of an $n$-dimensional Euclidean space, we investigate whether the motion group or the weak motion group of an $n$-dimensional affine metric space on a vector space $V$ over an arbitrary field admits a specific faithful linear representation as weak orthogonal group of an $(n+1)$-dimensional metric vector space. Apart from a few exceptions, such a representation exists precisely when the metric structure on $V$ is given by a quadratic form with a non-degenerate polar form.

[109] 2311.16786

A Logarithmic Weighted Adams-type inequality in the whole of $\mathbb{R}^{N}$ with an application

In this paper, we will establish a logarithmic weighted Adams inequality in a logarithmic weighted second order Sobolev space in the whole set of $\mathbb{R}^{N}$. Using this result, we delve into the analysis of a weighted fourth-order equation in $\mathbb{R}^{N}$. We assume that the non-linearity of the equation exhibits either critical or subcritical exponential growth, consistent with the Adams-type inequalities previously established. By applying the Mountain Pass Theorem, we demonstrate the existence of a weak solution to this problem. The primary challenge lies in the lack of compactness in the energy caused by the critical exponential growth of the non-linear term $f$.

[110] 2311.16795

Sensitivity analysis for sets : application to pollutant concentration maps

In the context of air quality control, our objective is to quantify the impact of uncertain inputs such as meteorological conditions and traffic parameters on pollutant dispersion maps. It is worth noting that the majority of sensitivity analysis methods are designed to deal with scalar or vector outputs and are ill suited to a map-valued output space. To address this, we propose two classes of methods. The first technique focuses on pointwise indices. Sobol indices are calculated for each position on the map to obtain Sobol index maps. Additionally, aggregated Sobol indices are calculated. Another approach treats the maps as sets and proposes a sensitivity analysis of a set-valued output with three different types of sensitivity indices. The first ones are inspired by Sobol indices but are adapted to sets based on the theory of random sets. The second ones adapt universal indices defined for a general metric output space. The last set indices use kernel-based sensitivity indices adapted to sets. The proposed methodologies are implemented to carry out an uncertainty analysis for time-averaged concentration maps of pollutants in an urban environment in the Greater Paris area. This entails taking into account uncertain meteorological aspects, such as incoming wind speed and direction, and uncertain traffic factors, such as injected traffic volume, percentage of diesel vehicles, and speed limits on the road network.

[111] 2311.16800

Temporal Entropy Evolution in Stochastic and Delayed Dynamics

We review the behaviour of the Gibbs' and conditional entropies in deterministic and stochastic systems with the added twist of a formulation appropriate for a stochastically perturbed system with {\it delayed} dynamics. The underlying question driving these investigations: ``Is the origin of the universally observed unidirectionality of time in our universe connected to the behaviour of entropy?" We focus on temporal entropic behaviour with a review of previous results in deterministic and stochastic systems. Our emphasis is on the temporal behaviour of the Gibbs' and conditional entropies as they give equilibrium results in concordance with experimental findings. In invertible deterministic systems both entropies are temporally constant as has been well known for decades. The addition of stochastic perturbations (Wiener process) leads to an indeterminate (either increasing or decreasing) behaviour of the Gibbs' entropy, but the conditional entropy monotonically approaches equilibrium with increasing time. The presence of delays in the dynamics, whether stochastically perturbed or not, leads to situations in which the Gibbs' and conditional entropies evolution can be oscillatory and not monotone, and may not approach equilibrium.

[112] 2311.16806

Summing the sum of digits

We revisit and generalize inequalities for the summatory function of the sum of digits in a given integer base. We prove that several known results can be deduced from a theorem in a 2023 paper by Mohanty, Greenbury, Sarkany, Narayanan, Dingle, Ahnert, and Louis, whose primary scope is the maximum mutational robustness in genotype-phenotype maps.

[113] 2311.16814

Reflexive symmetric differentials and quotients of bounded symmetric domains

For each classical irreducible bounded symmetric domain $\mathcal{D}$, Klingler has computed the minimum number $m_{\mathcal{D}}$ such that any smooth projective quotient $X=\mathcal{D}/\Gamma$, for $\Gamma\in\textrm{Aut}^0(\mathcal{D})$, satisfies $H^0(X,\mathrm{Sym}^i\Omega^1_X)=0$ for $0

[114] 2311.16816

Packing even directed circuits quarter-integrally

We prove the existence of a computable function $f\colon\mathbb{N}\to\mathbb{N}$ such that for every integer $k$ and every digraph $D$ either contains a collection $\mathcal{C}$ of directed cycles of even length such that no vertex of $D$ belongs to more than four cycles in $\mathcal{C}$, or there exists a set $S\subseteq V(D)$ of size at most $f(k)$ such that $D-S$ has no directed cycle of even length. Moreover, we provide an algorithm that finds one of the two outcomes of this statement in time $g(k)n^{\mathcal{O}(1)}$ for some computable function $g\colon \mathbb{N}\to\mathbb{N}$. Our result unites two deep fields of research from the algorithmic theory for digraphs: The study of the Erd\H{o}s-P\'osa property of digraphs and the study of the Even Dicycle Problem. The latter is the decision problem which asks if a given digraph contains an even dicycle and can be traced back to a question of P\'olya from 1913. It remained open until a polynomial time algorithm was finally found by Robertson, Seymour, and Thomas (Ann. of Math. (2) 1999) and, independently, McCuaig (Electron. J. Combin. 2004; announced jointly at STOC 1997). The Even Dicycle Problem is equivalent to the recognition problem of Pfaffian bipartite graphs and has applications even beyond discrete mathematics and theoretical computer science. On the other hand, Younger's Conjecture (1973), states that dicycles have the Erd\H{o}s-P\'osa property. The conjecture was proven more than two decades later by Reed, Robertson, Seymour, and Thomas (Combinatorica 1996) and opened the path for structural digraph theory as well as the algorithmic study of the directed feedback vertex set problem. Our approach builds upon the techniques used to resolve both problems and combines them into a powerful structural theorem that yields further algorithmic applications for other prominent problems.

[115] 2311.16827

On the Dualizability of Fusion 2-Categories, and the Relative 2-Deligne Tensor Product

Over an arbitrary field, we prove that the relative 2-Deligne tensor product of two separable module 2-categories over a compact semisimple tensor 2-category exists. This allows us to consider the Morita 4-category of compact semisimple tensor 2-categories, separable bimodule 2-categories, and their morphisms. Categorifying a result of arXiv:1312.7188, we prove that separable compact semisimple tensor 2-categories are fully dualizable objects therein. In particular, it then follows from the main theorem of arXiv:2211.04917 that, over an algebraically closed field of characteristic zero, every fusion 2-category is a fully dualizable object of the above Morita 4-category. We explain how this result can be extended to any field of characteristic zero. As another application of the relative 2-Deligne tensor product, we outline extension theory for compact semisimple tensor 2-categories, which we use to classify fermionic strongly fusion 2-categories over an algebraically closed field of characteristic zero.

[116] 2311.16846

Normalized Ground State Solutions for Fractional Schrodinger Systems with General Nonlinearities

Normalized ground state solutions (NGSS) of Schrodinger equations (SE) have attracted the attention of many research groups during the last decades. This is essentially due to their relevance in many fields in physics and engineering, where the stable and most attractive solutions happen to be the normalized ones. For a single (SE), recent developments lead to the establishment of existence and non-existence results for a wide range of natural nonlinearities in (SE) in the sub-critical, critical and super-critical regimes. However for systems of (SE), there are still many interesting open questions for basic nonlinearities. It certainly requires innovative ideas to shed some light to treat these complex situations. So far, only a very few specific nonlinearities have been addressed. Unlike the single (SE), the corresponding strict sub-additivity inequality is challenging and an improved concentration-compactness theorem is critical to treat (NGSS) of systems of (SE). The aim of this paper is to establish the existence of (NGSS) for a large class of nonlinearities. This class includes many relevant pure-power type nonlinearities and can be easily extended to Hartree type nonlinearities (and a combination of both). The presence of the fractional Laplacian adds a considerable difficulty to rule out the dichotomy. We were able to overcome this challenge and establish very general assumptions ensuring the strict subadditivity of the constrained energy functional. We believe that our approach will open the door to many unresolved problems.

[117] 2311.16850

General Derivative-Free Optimization Methods under Global and Local Lipschitz Continuity of Gradients

This paper addresses the study of derivative-free smooth optimization problems, where the gradient information on the objective function is unavailable. Two novel general derivative-free methods are proposed and developed for minimizing such functions with either global or local Lipschitz continuous gradients. The newly developed methods use gradient approximations based on finite differences, where finite difference intervals are automatically adapted to the magnitude of the exact gradients without knowing them exactly. The suggested algorithms achieve fundamental convergence results, including stationarity of accumulation points in general settings as well as global convergence with constructive convergence rates when the Kurdyka-\L ojasiewicz property is imposed. The local convergence of the proposed algorithms to nonisolated local minimizers, along with their local convergence rates, is also analyzed under this property. Numerical experiences involving various convex, nonconvex, noiseless, and noisy functions demonstrate that the new methods exhibit essential advantages over other state-of-the-art methods in derivative-free optimization.

[118] 2311.16852

Optimal minimax rate of learning interaction kernels

Nonparametric estimation of nonlocal interaction kernels is crucial in various applications involving interacting particle systems. The inference challenge, situated at the nexus of statistical learning and inverse problems, comes from the nonlocal dependency. A central question is whether the optimal minimax rate of convergence for this problem aligns with the rate of $M^{-\frac{2\beta}{2\beta+1}}$ in classical nonparametric regression, where $M$ is the sample size and $\beta$ represents the smoothness exponent of the radial kernel. Our study confirms this alignment for systems with a finite number of particles. We introduce a tamed least squares estimator (tLSE) that attains the optimal convergence rate for a broad class of exchangeable distributions. The tLSE bridges the smallest eigenvalue of random matrices and Sobolev embedding. This estimator relies on nonasymptotic estimates for the left tail probability of the smallest eigenvalue of the normal matrix. The lower minimax rate is derived using the Fano-Tsybakov hypothesis testing method. Our findings reveal that provided the inverse problem in the large sample limit satisfies a coercivity condition, the left tail probability does not alter the bias-variance tradeoff, and the optimal minimax rate remains intact. Our tLSE method offers a straightforward approach for establishing the optimal minimax rate for models with either local or nonlocal dependency.

[119] 2311.16859

Symplectic higher Auslander correspondence for type A

We prove that the Fukaya-Seidel categories of a certain family of singularities on $\mathbb{C}^d$ are equivalent to the perfect derived categories of higher Auslander algebras of Dynkin type A. We relate these to the Fukaya-Seidel categories of Brieskorn-Pham singularities and to the partially wrapped Fukaya categories considered by Dyckerhoff-Jasso-Lekili. We provide a symplectic interpretation to higher Auslander correspondence of type A in terms of Fukaya-Seidel categories of Lefschetz fibrations.

[120] 2311.16861

Two Positive Normalized Solutions and Phase Separation for Coupled Schrödinger Equations on Bounded Domain with L2-Supercritical and Sobolev Critical or Subcritical Exponent

In this paper we study the existence of positive normalized solutions of the following coupled Schr\"{o}dinger system: \begin{align} \left\{ \begin{aligned} & -\Delta u = \lambda_u u + \mu_1 u^3 + \beta uv^2, \quad x \in \Omega, \\ & -\Delta v = \lambda_v v + \mu_2 v^3 + \beta u^2 v, \quad x \in \Omega, \\ & u > 0, v > 0 \quad \text{in } \Omega, \quad u = v = 0 \quad \text{on } \partial\Omega, \end{aligned} \right. \nonumber \end{align} with the $L^2$ constraint \begin{align} \int_{\Omega}|u|^2dx = c_1, \quad \quad \int_{\Omega}|v|^2dx = c_2, \nonumber \end{align} where $\mu_1, \mu_2 > 0$, $\beta \neq 0$, $c_1, c_2 > 0$, and $\Omega \subset \mathbb{R}^N$ ($N = 3, 4$) is smooth, bounded, and star-shaped. Note that the nonlinearities and the coupling terms are both $L^2$-supercritical in dimensions 3 and 4, Sobolev subcritical in dimension 3, Sobolev critical in dimension 4. We show that this system has a positive normalized solution which is a local minimizer. We further show that the system has a second positive normalized solution, which is of M-P type when $N = 3$. This seems to be the first existence result of two positive normalized solutions for such a Schr\"{o}dinger system, especially in the Sobolev critical case. We also study the limit behavior of the positive normalized solutions in the repulsive case $\beta \to -\infty$, and phase separation is expected.

[121] 2311.16870

Unit Reducible Cyclotomic Fields

In this paper, we continue the study of unit reducible fields as introduced in \cite{LPL23} for the special case of cyclotomic fields. Specifically, we deduce that the cyclotomic fields of conductors $2,3,5,7,8,9,12,15$ are all unit reducible, and show that any cyclotomic field of conductor $N$ is not unit reducible if $2^4, 3^3, 5^2, 7^2, 11^2$ or any prime $p \geq 13$ divide $N$, meaning the unit reducible cyclotomic fields are finite in number. Finally, if $a$ is a totally positive element of a cyclotomic field, we show that for all equivalent $a^\prime$, the discrepancy between $\trace_{K/\mathbb{Q}}(a^\prime)$ and the shortest nonzero element of the quadratic form $\trace_{K/\mathbb{Q}}(axx^*)$ where $x$ is taken from the ring of integers tends to infinity as the conductor $N$ goes to infinity.

[122] 2311.16871

Improvements on dimension growth results and effective Hilbert's irreducibility theorem

We sharpen and generalize the dimension growth bounds for the number of points of bounded height lying on an irreducible algebraic variety of degree $d$, over any global field. In particular, we focus on the the affine hypersurface situation by relaxing the condition on the top degree homogeneous part of the polynomial describing the affine hypersurface. Our work sharpens the dependence on the degree in the bounds, compared to~\cite{CCDN-dgc}. We also formulate a conjecture about plane curves which gives a conjectural approach to the uniform degree $3$ case (the only case which remains open). For induction on dimension, we develop a higher dimensional effective version of Hilbert's irreducibility theorem.

[123] 2311.16880

Using a Grassmann graph to recover the underlying projective geometry

Let $n,k$ denote integers with $n>2k\geq 6$. Let $\mathbb{F}_q$ denote a finite field with $q$ elements, and let $V$ denote a vector space over $\mathbb{F}_q$ that has dimension $n$. The projective geometry $P_q(n)$ is the partially ordered set consisting of the subspaces of $V$; the partial order is given by inclusion. For the Grassman graph $J_q(n,k)$ the vertex set consists of the $k$-dimensional subspaces of $V$. Two vertices of $J_q(n,k)$ are adjacent whenever their intersection has dimension $k-1$. The graph $J_q(n,k)$ is known to be distance-regular. Let $\partial$ denote the path-length distance function of $J_q(n,k)$. Pick two vertices $x,y$ in $J_q(n,k)$ such that $1<\partial(x,y)

[124] 2311.16881

(Non-)vanishing results for extensions between simple outer functors

We study Ext groups between certain polynomial outer functors, inspired by an earlier result of Vespa in a related context. We prove certain vanishing results for these groups, and show that a Koszul-type property implied by Vespa's result no longer holds when we pass to the category of polynomial outer functors.

[125] 2311.16884

Statistical inference for a service system with non-stationary arrivals and unobserved balking

We study a multi-server queueing system with a periodic arrival rate and customers whose joining decision is based on their patience and a delay proxy. Specifically, each customer has a patience level sampled from a common distribution. Upon arrival, they receive an estimate of their delay before joining service and then join the system only if this delay is not more than their patience, otherwise they balk. The main objective is to estimate the parameters pertaining to the arrival rate and patience distribution. Here the complication factor is that this inference should be performed based on the observed process only, i.e., balking customers remain unobserved. We set up a likelihood function of the state dependent effective arrival process (i.e., corresponding to the customers who join), establish strong consistency of the MLE, and derive the asymptotic distribution of the estimation error. Due to the intrinsic non-stationarity of the Poisson arrival process, the proof techniques used in previous work become inapplicable. The novelty of the proving mechanism in this paper lies in the procedure of constructing i.i.d. objects from dependent samples by decomposing the sample path into i.i.d.\ regeneration cycles. The feasibility of the MLE-approach is discussed via a sequence of numerical experiments, for multiple choices of functions which provide delay estimates. In particular, it is observed that the arrival rate is best estimated at high service capacities, and the patience distribution is best estimated at lower service capacities.

[126] 2311.16891

String topology on the space of paths with endpoints in a submanifold

In this article we consider algebraic structures on the homology of the space of paths in a manifold with endpoints in a submanifold. The product on the homology of this space had already been investigated by Hingston and Oancea for a particular example. We show that this product can be understood well if the embedding of the submanifold is null-homotopic. Moreover, the homology of the space of paths in a manifold with endpoints in a submanifold is a module over the Chas-Sullivan ring of the manifold. If the manifold is a sphere or a Lie group and the inclusion of the submanifold is null-homotopic then we prove that the homology of the space of paths with endpoints in the submanifold is even an algebra over the Chas-Sullivan ring. We also study a counterexample which shows that this property does not hold in general.

[127] 2311.16898

On the existence of optimal multi-valued decoders and their accuracy bounds for undersampled inverse problems

Undersampled inverse problems occur everywhere in the sciences including medical imaging, radar, astronomy etc., yielding underdetermined linear or non-linear reconstruction problems. There are now a myriad of techniques to design decoders that can tackle such problems, ranging from optimization based approaches, such as compressed sensing, to deep learning (DL), and variants in between the two techniques. The variety of methods begs for a unifying approach to determine the existence of optimal decoders and fundamental accuracy bounds, in order to facilitate a theoretical and empirical understanding of the performance of existing and future methods. Such a theory must allow for both single-valued and multi-valued decoders, as underdetermined inverse problems typically have multiple solutions. Indeed, multi-valued decoders arise due to non-uniqueness of minimizers in optimisation problems, such as in compressed sensing, and for DL based decoders in generative adversarial models, such as diffusion models and ensemble models. In this work we provide a framework for assessing the lowest possible reconstruction accuracy in terms of worst- and average-case errors. The universal bounds bounds only depend on the measurement model $F$, the model class $\mathcal{M}_1 \subseteq \mathcal{X}$ and the noise model $\mathcal{E}$. For linear $F$ these bounds depend on its kernel, and in the non-linear case the concept of kernel is generalized for undersampled settings. Additionally, we provide multi-valued variational solutions that obtain the lowest possible reconstruction error.

[128] 2311.16899

On the saturation spectrum of the unions of disjoint cycles

Let $G$ be a graph and $\mathcal{H}$ be a family of graphs. We say $G$ is $\mathcal{H}$-saturated if $G$ does not contain a copy of $H$ with $H\in\mathcal{H}$, but the addition of any edge $e\notin E(G)$ creates at least one copy of some $H\in\mathcal{H}$ within $G+e$. The saturation number of $\mathcal{H}$ is the minimum size of an $\mathcal{H}$-saturated graph on $n$ vertices, and the saturation spectrum of $\mathcal{H}$ is the set of all possible sizes of an $\mathcal{H}$-saturated graph on $n$ vertices. Let $k\mathcal{C}_{\ge 3}$ be the family of the unions of $k$ vertex-disjoint cycles. In this note, we completely determine the saturation number and the saturation spectrum of $k\mathcal{C}_{\ge 3}$ for $k=2$ and give some results for $k\ge 3$.

[129] 2311.16910

An explicit construction for large sets of infinite dimensional $q$-Steiner systems

Let $V$ be a vector space over the finite field ${\mathbb F}_q$. A $q$-Steiner system, or an $S(t,k,V)_q$, is a collection ${\mathcal B}$ of $k$-dimensional subspaces of $V$ such that every $t$-dimensional subspace of $V$ is contained in a unique element of ${\mathcal B}$. A large set of $q$-Steiner systems, or an $LS(t,k,V)_q$, is a partition of the $k$-dimensional subspaces of $V$ into $S(t,k,V)_q$ systems. In the case that $V$ has infinite dimension, the existence of an $LS(t,k,V)_q$ for all finite $t,k$ with $1

[130] 2311.16921

Comparing intrusive and non-intrusive polynomial chaos for a class of exponential time differencing schemes

We consider the numerical approximation of different ordinary differential equations (ODEs) and partial differential equations (PDEs) with periodic boundary conditions involving a one-dimensional random parameter, comparing the intrusive and non-intrusive polynomial chaos expansion (PCE) method. We demonstrate how to modify two schemes for intrusive PCE (iPCE) which are highly efficient in solving nonlinear reaction-diffusion equations: A second-order exponential time differencing scheme (ETD-RDP-IF) as well as a spectral exponential time differencing fourth-order Runge-Kutta scheme (ETDRK4). In numerical experiments, we show that these schemes show superior accuracy to simpler schemes such as the EE scheme for a range of model equations and we investigate whether they are competitive with non-intrusive PCE (niPCE) methods. We observe that the iPCE schemes are competitive with niPCE for some model equations, but that iPCE breaks down for complex pattern formation models such as the Gray-Scott system.

[131] 2311.16924

Fill-ins with scalar curvature lower bounds and applications to positive mass theorems

Given a constant C and a smooth closed $(n-1)$-dimensional Riemannian manifold $(\Sigma, g)$ equipped with a positive function $H$, a natural question to ask is whether this manifold can be realised as the boundary of a smooth $n$-dimensional Riemannian manifold with scalar curvature bounded below by C. That is, does there exist a fill-in of $(\Sigma,g,H)$ with scalar curvature bounded below by C? We use variations of an argument due to Miao and the author [arXiv:1701.04805] to explicitly construct fill-ins with different scalar curvature lower bounds, where we permit the fill-in to contain another boundary component provided it is a minimal surface. Our main focus is to illustrate the applications of such fill-ins to geometric inequalities in the context of general relativity. By filling in a manifold beyond a boundary, one is able to obtain lower bounds on the mass in terms of the boundary geometry through positive mass theorems and Penrose inequalities. We consider fill-ins with both positive and negative scalar curvature lower bounds, which from the perspective of general relativity corresponds to the sign of the cosmological constant, as well as a fill-in suitable for the inclusion of electric charge.

[132] 2311.16928

Pointwise Ergodic Theorems for Uniformly Behaved in ${\mathbb N}$ Sequences

We define a uniformly behaved in ${\mathbb N}$ arithmetic sequence ${\bf a}$. We give several examples, including the counting function of the prime factors in natural numbers, the Thue-Morse sequence, the Rudin-Shapiro sequence, the sequence of even (or odd) prime factor natural numbers, and the sequence of square-free natural numbers. We define an ${\bf a}$-mean Lyapunov stable dynamical system $f$. We consider the mean partial sum of a continuous function $\phi$ over the ${\bf a}$-orbit of $f$ up to ${\mathbb N}$. The main result we prove in the paper is that the mean partial sum converges pointwise if ${\bf a}$ is uniformly behaved in ${\mathbb N}$ and $f$ is minimal and uniquely ergodic and ${\bf a}$-mean Lyapunov stable. In addition, if ${\bf a}$ is also completely additive or multiplicative, we then prove that the mean partial sum of a continuous function $\phi$ over the square-free ${\bf a}$-orbit of $f$ up to ${\mathbb N}$ converges pointwise too. We derive other consequences from the main result relevant to dynamical systems/ergodic theory and number theory.

[133] 2311.16930

About a Proposition on Escobar's paper "The Geometry of the First Non-zero Stekloff Eigenvalue''

Let $(M^{2},g_{0})$ be a compact manifold with boundary, and let $g$ and $g_{0}$ be conformally related by $g=e^{2f}g_{0}$. We show that the inequality $$\nu_{1}(g)\geq\Big(\max_{x\in\partial M}e^{-f(x)}\Big)\nu_{1}(g_{0})$$ stated in Proposition 2 in \cite{Escobar1}, is only possible when the equality is achieved. In order to achieve such equality, it is required that the function $f$ be constant on $\partial M$, as it is mentioned in \textit{Remark 3} also in \cite{Escobar1}. Hence, the scope of this inequality is less broad than the one suggested by the Proposition.

[134] 2311.16939

Decomposition numbers for unipotent blocks with small $\mathfrak{sl}_2$-weight in finite classical groups

We show that parabolic Kazhdan-Lusztig polynomials of type $A$ compute the decomposition numbers in certain Harish-Chandra series of unipotent characters of finite groups of Lie types $B$, $C$ and $D$ over a field of non-defining characteristic $\ell$. Here, $\ell$ is a ``unitary prime" -- the case that remains open in general. The bipartitions labeling the characters in these series are small with respect to $d$, the order of $q$ mod $\ell$, although they occur in blocks of arbitrarily high defect. Our main technical tool is the categorical action of an affine Lie algebra on the category of unipotent representations, which identifies the branching graph for Harish-Chandra induction with the $\widehat{\mathfrak{sl}}_d$-crystal on a sum of level $2$ Fock spaces. Further key combinatorics has been adapted from Brundan and Stroppel's work on Khovanov arc algebras to obtain the closed formula for the decomposition numbers in a $d$-small Harish-Chandra series.

[135] 2311.16947

An $A_\infty$-version of the Eilenberg-Moore theorem

We construct an $A_\infty$-structure on the two-sided bar construction involving homotopy Gerstenhaber algebras (hgas). It extends the non-associative product defined by Carlson and the author and generalizes the dga structure on the one-sided bar construction due to Kadeishvili-Saneblidze. As a consequence, the multiplicative cohomology isomorphism from the Eilenberg-Moore theorem is promoted to a quasi-isomorphism of $A_\infty$-algebras. We also show that the resulting product on the differential torsion product involving cochain algebras agrees with the one defined by Eilenberg-Moore and Smith, for all triples of spaces. This is a consequence of the following result, which is of independent interest: The strongly homotopy commutative (shc) structure on cochains inductively constructed by Gugenheim-Munkholm agrees with the one previously defined by the author for all hgas.

[136] 2311.16949

Convex hull property for elliptic and parabolic systems of PDE

We study the convex hull property for systems of partial differential equations. This is a generalisation of the maximum principle for a single equation. We show that the convex hull property holds for a class of elliptic and parabolic systems of non-linear partial differential equations. In particular, this includes the case of the parabolic $p$-Laplace system. The coupling conditions for coefficients are demonstrated to be optimal by means of respective counterexamples.

[137] 2311.16956

Adaptive Step Sizes for Preconditioned Stochastic Gradient Descent

This paper proposes a novel approach to adaptive step sizes in stochastic gradient descent (SGD) by utilizing quantities that we have identified as numerically traceable -- the Lipschitz constant for gradients and a concept of the local variance in search directions. Our findings yield a nearly hyperparameter-free algorithm for stochastic optimization, which has provable convergence properties when applied to quadratic problems and exhibits truly problem adaptive behavior on classical image classification tasks. Our framework enables the potential inclusion of a preconditioner, thereby enabling the implementation of adaptive step sizes for stochastic second-order optimization methods.

[138] 2311.16962

Direct Imaging Methods for Inverse Obstacle Scattering

Direct imaging methods recover the presence, position, and shape of the unknown obstacles in time-harmonic inverse scattering without a priori knowledge of either the physical properties or the number of disconnected components of the scatterer, i.e., on the boundary condition. However, most of these methods require multi-static data and only obtain partial information about the obstacle. These qualitative methods are based on constructing indicator functions defined on the domain of interest, which help determine whether a spatial point or point source lies inside or outside the scatterer. This paper explains the main themes of each of these methods, with emphasis on highlighting the advantages and limitations of each scheme. Additionally, we will classify each method and describe how some of these methods are closely related to each other.

[139] 2311.16970

Well-posedness for a molecular beam epitaxy model

We study a general molecular beam epitaxy (MBE) equation modeling the epitaxial growth of thin films. We show that, in the deterministic case, the associated Cauchy problem admits a unique smooth solution for all time, given initial data in the space $X_0 = L^{2}(R^{d}) \cap \dot{W}^{1,4}(R^{d})$ with $d = 1, 2$. This improves a recent result by Ag\'elas, who established global existence in $H^{3}(R^{d})$. Moreover, we investigate the local existence and uniqueness of solutions in the space $X_0$ for the stochastic MBE equation, with an additive noise that is white in time and regular in the space variable.

[140] 2311.16971

Generalized Products and Semiclassical Quantization

The notion of a generalized product, refining that of a (symmetric and smooth) simplicial space is introduced and shown to imply the existence of an algebra of pseudodifferential operators. This encompasses many constructions of such algebras on manifolds with corners. The main examples discussed in detail here are related to the semiclassical (and adiabatic) calculus as used in the approach to a twisted form of the Atiyah-Singer index theorem in work with Is Singer and Mathai Varghese.

[141] 2311.16972

The invariant $λ_2$ from graph configurations

For an oriented rational homology sphere $M$, the logarithm of the Kontsevich-Kuperberg-Thurston invariant $z_{KKT}(M)$ counts embeddings of connected trivalent graphs in $M$, using integrals on configuration spaces of points in $M$. It is a universal finite type invariant of oriented rational homology spheres. The quantity $\exp(z_{KKT})$ is often called the perturbative expansion of the Chern-Simons theory. In this article, we give an independent original definition of the degree two part of $z_{KKT}$ appropriate for concrete computations. This article can also serve as an introduction to the definition of $z_{KKT}$.

[142] 2311.16975

Managing Vehicle Charging During Emergencies via Conservative Distribution System Modeling

Combinatorial distribution system optimization problems, such as scheduling electric vehicle (EV) charging during evacuations, present significant computational challenges. These challenges stem from the large numbers of constraints, continuous variables, and discrete variables, coupled with the unbalanced nature of distribution systems. In response to the escalating frequency of extreme events impacting electric power systems, this paper introduces a method that integrates sample-based conservative linear power flow approximations (CLAs) into an optimization framework. In particular, this integration aims to ameliorate the aforementioned challenges of distribution system optimization in the context of efficiently minimizing the charging time required for EVs in urban evacuation scenarios.

[143] 2311.16979

Mirković-Vilonen Polytopes from Combinatorics

Mirkovi\'c-Vilonen (MV) polytopes are a class of generalized permutahedra originating from geometric representation theory. In this paper we study MV polytopes coming from matroid polytopes, flag matroid polytopes, Bruhat interval polytopes, and Schubitopes. We give classifications and combinatorial conditions for when these polytopes are MV polytopes. We also describe how the crystal structure on MV polytopes manifests combinatorially in these situations. As a special case, we show that the Newton polytopes of Schubert polynomials and key polynomials are MV polytopes.

[144] 2311.16986

Multi-population opinion dynamics model

We introduce multi-population opinion dynamics models linked to the bounded confidence model, aiming to explore how interactions between individuals contribute to the emergence of consensus, polarization, or fragmentation. Existing models either neglect agent similarities, sacrificing accuracy for scalability, or prioritize accuracy by introducing agent-wise connections, constraining scalability. Our proposed model captures similarities between agents in scalable matter. In our setting, agents similarities are defined by their group affiliations. Specifically, each sub-population is characterized by its distribution, and the closeness between two sub-populations is measured by the Wasserstein distance of their corresponding distributions. This leads to two mutually connected dynamics: micro, the individual-based dynamics, and the macro, the distribution-based one. The individual-wise interactions take into account the population-wise interactions (similarities), and the population-wise interactions are updated based on the individual-wise interactions. We have proven the well-posedness of our models. Additionally, we conducted several simulations to mimic certain complex social phenomena.

[145] 2311.16987

A Non-Archimedean Approach to Stratifications

These are notes from a mini-course about the main results of arXiv:2206.03438: I explain how, using suitable valued fields, one obtains a natural notion of canonical stratifications (of e.g. algebraic subsets of $\mathbb{R}^n$). I also explain how the same techniques yield more invariants of singularities, and I present an application to Poincar\'e series. While some rudimentary knowledge of model theory is useful, the notes should also be accessible without such knowledge. In particular, they contain an introduction to the non-standard analysis needed for this approach.

[146] 2311.16990

(Co)Homology of Partial Smash Products

Given a cocommutative Hopf algebra $\mathcal{H}$ over a commutative ring $K$ and a symmetric partial action of $\mathcal{H}$ on a $K$-algebra $A,$ we obtain a first quadrant Grothendieck spectral sequence converging to the Hochschild homology of the smash product $A \# \mathcal{H},$ involving the Hochschild homology of $A$ and the partial homology of $\mathcal{H}.$ An analogous third quadrant cohomological spectral sequence is also obtained. The definition of the partial (co)homology of $\mathcal{H}$ under consideration is based on the category of the partial representations of $\mathcal{H}.$ A specific partial representation of $\mathcal{H}$ on a subalgebra $\mathcal{B}$ of the partial ``Hopf" algebra $\mathcal{H}_{par} $ is involved in the definition and we construct a projective resolution of $\mathcal{B}.$

[147] 2311.16999

The twisted partial group algebra and (co)homology of partial crossed products

Given a group $G$ and a partial factor set $\sigma $ of $G,$ we introduce the twisted partial group algebra $\kappa_{par}^{\sigma}G,$ which governs the partial projective $\sigma$-representations of $G$ into algebras over a filed $\kappa.$ Using the relation between partial projective representations and twisted partial actions we endow $\kappa_{par}^\sigma G$ with the structure of a crossed product by a twisted partial action of $G$ on a commutative subalgebra of $\kappa_{par}^{\sigma} G.$ Then, we use twisted partial group algebras to obtain a first quadrant Grothendieck spectral sequence converging to the Hochschild homology of the crossed product $A\ast_{\Theta} G,$ involving the Hochschild homology of $A$ and the partial homology of $G,$ where ${\Theta}$ is a unital twisted partial action of $G$ on a $\kappa$-algebra $A$ with a $\kappa $-based twist. An analogous third quadrant cohomological spectral sequence is also obtained.

[148] 2311.17003

Rigidity and Schofield's partial tilting conjecture for quiver moduli

We explain how Teleman quantization can be applied to moduli spaces of quiver representations to compute the higher cohomology of the endomorphism bundle of the universal bundle. We use this to prove Schofield's partial tilting conjecture, and to show that moduli spaces of quiver representations are (infinitesimally) rigid as varieties.

[149] 2311.17004

Vector fields and admissible embeddings for quiver moduli

We introduce a double framing construction for moduli spaces of quiver representations. It allows us to reduce certain sheaf cohomology computations involving the universal representation, to computations involving line bundles, making them amenable to methods from geometric invariant theory. We will use this to show that in many good situations the vector fields on the moduli space are isomorphic as a vector space to the first Hochschild cohomology of the path algebra. We also show that considering the universal representation as a Fourier-Mukai kernel in the appropriate sense gives an admissible embedding of derived categories.

[150] 2311.17014

$2$-rotund norms for generalized Baernstein spaces and their duals

We consider a generalized Baernstein space associated to a compact family of finite subsets of an uncountable set. We show that for certain transfinitely defined families such spaces admit an equivalent $2$-rotund norm. We also show that for an arbitrary family the dual space admits an equivalent $2$-rotund norm.

[151] 2311.17025

Automorphisms of the procongruence pants complex

We show that every automorphism of the congruence completion of the extended mapping class group which preserves the set of conjugacy classes of procyclic groups generated by Dehn twists is inner and that their automorphism group is naturally isomorphic to the automorphism group of the procongruence pants complex. In the genus $0$ case, we prove the stronger result that all automorphism of the profinite completion of the extended mapping class group are inner.

[152] 2311.17028

The Akbulut cork is not universal

We exhibit infinitely many exotic pairs of simply-connected, closed $4$-manifolds not related by any cork of the infinite family $W_n$ constructed by Akbulut and Yasui whose first member is the Akbulut cork. In particular, the Akbulut cork is not universal. Moreover we show that, in the setting of manifolds with boundary, there are no $\partial$-universal corks, i.e. there does not exist a cork which relates any exotic pair of simply-connected $4$-manifolds with boundary.

[153] 2311.17029

Decomposition of Symplectic Vector Bundles and Azumaya Algebras

Let $X$ be a connected CW complex. Let $\mathcal{V}$ be a symplectic vector bundle of rank $2mn$ over $X$, and let $\mathcal{A}$ be a topological Azumaya algebra of degree $2mn$ with a symplectic involution over a $X$. We give conditions for the positive integers $m$ and $n$, and the dimension of $X$ so that $\mathcal{V}$ can be decomposed as the tensor product of a symplectic vector bundle of rank $2m$ and an orthogonal vector bundle of rank $n$; and so that $\mathcal{A}$ can be decomposed as the tensor product of topological Azumaya algebras of degrees $2m$ and $n$ with involutions of the first kind.

[154] 2311.17031

Heegaard Floer Symplectic homology and Viterbo's isomorphism theorem in the context of multiple particles

Given a Liouville manifold $M$, we introduce an invariant of $M$ that we call the Heegaard Floer symplectic cohomology $SH^*_\kappa(M)$ for any $\kappa \ge 1$ that coincides with the symplectic cohomology for $\kappa=1$. Writing $\hat{M}$ for the completion of $M$, the differential counts pseudoholomorphic curves of arbitrary genus in $\mathbb{R} \times S^1 \times \hat{M}$ that are required to be branched $\kappa$-sheeted covers when projected to the $\mathbb{R} \times S^1$-direction; this resembles the cylindrical reformulation of Heegaard Floer homology by Lipshitz. These cohomology groups provide a closed-string analogue of higher-dimensional Heegaard Floer homology introduced by Colin, Honda, and Tian. When $\hat{M}=T^*Q$ with $Q$ an orientable manifold, we introduce a Morse-theoretic analogue of Heegaard Floer symplectic cohomology, which we call the free multiloop complex of $Q$. When $Q$ has vanishing relative second Stiefel-Whitney class, we prove a generalized version of Viterbo's isomorphism theorem by showing that the cohomology groups $SH^*_\kappa(T^*Q)$ are isomorphic to the cohomology groups of the free multiloop complex of $Q$.

[155] 2311.17032

Stability estimates of Nyström discretizations of Helmholtz decomposition boundary integral equation formulations for the solution of Navier scattering problems in two dimensions with Dirichlet boundary conditions

Helmholtz decompositions of elastic fields is a common approach for the solution of Navier scattering problems. Used in the context of Boundary Integral Equations (BIE), this approach affords solutions of Navier problems via the simpler Helmholtz boundary integral operators (BIOs). Approximations of Helmholtz Dirichlet-to-Neumann (DtN) can be employed within a regularizing combined field strategy to deliver BIE formulations of the second kind for the solution of Navier scattering problems in two dimensions with Dirichlet boundary conditions, at least in the case of smooth boundaries. Unlike the case of scattering and transmission Helmholtz problems, the approximations of the DtN maps we use in the Helmholtz decomposition BIE in the Navier case require incorporation of lower order terms in their pseudodifferential asymptotic expansions. The presence of these lower order terms in the Navier regularized BIE formulations complicates the stability analysis of their Nystr\"om discretizations in the framework of global trigonometric interpolation and the Kussmaul-Martensen kernel singularity splitting strategy. The main difficulty stems from compositions of pseudodifferential operators of opposite orders, whose Nystr\"om discretization must be performed with care via pseudodifferential expansions beyond the principal symbol. The error analysis is significantly simpler in the case of arclength boundary parametrizations and considerably more involved in the case of general smooth parametrizations which are typically encountered in the description of one dimensional closed curves.

[156] 2311.17033

Harmonic Functions on Four Dimensions

This paper develops theory for a newly-defined bicomplex hyperbolic harmonic function with four real-dimensional inputs, in a way that generalizes the connection between real harmonic functions with two real-dimensional inputs and complex analytic functions. For example, every bicomplex hyperbolic harmonic function appears as this paper's newly-defined hyperbolic real part of a bicomplex analytic function, just as every real harmonic function with two real-dimensional inputs is the real part of a complex analytic function. In addition, this connection produces a unique (up to additive constant) and newly-defined hyperbolic harmonic conjugate function, just as every real harmonic function has a unique (up to additive constant) real harmonic conjugate. Finally, the paper determines a bicomplex Poisson kernel function that produces a corresponding integral representation for bicomplex harmonic functions, one that generalizes the complex harmonic function Poisson integral representation.

[157] 2311.17036

The Aizenbud-Lapid binary operation for symmetrizable Cartan types

Aizenbud and Lapid recently introduced a binary operation on the crystal graph $B(-\infty)$ associated to a symmetric Cartan matrix. We extend their construction to symmetrizable Cartan matrices and strengthen a cancellation property of the binary operation.

[158] 2311.17045

Jets of foliations and $b^k$-algebroids

In this article, we introduce and study singular foliations of $b^k$-type. These singular foliations formalize the properties of vector fields that are tangent to order $k$ along a submanifold $W \subset M$. Our first result is a classification of these foliations, relating them to geometric structures defined in a formal neighborhood of the submanifold, such as jets of distributions that are involutive up to order $k-1$. When $W$ is a hypersurface, singular foliations of $b^k$-type are Lie algebroids. In this particular case, they are generalizations of the $b^k$-tangent bundles introduced by Scott. Indeed, they are always locally isomorphic to $b^k$-tangent bundles, but globally such an isomorphism is obstructed by a holonomy invariant. Our second main result is a Riemann-Hilbert-style classification of singular foliations of $b^k$-type in terms of holonomy representations. In this paper, we study singular foliations of $b^k$-type from several different perspectives. In particular: (1) We study the problem of extending a $k$-th-order foliation to a $(k+1)$-th order foliation and prove that this is obstructed by a characteristic class. (2) When $W$ is a hypersurface, we give a detailed study of algebroid differential forms and extend Scott's calculation of the cohomology. (3) We study algebroid symplectic forms in terms of the geometric structures induced on $W$. In particular, we find that there is a close relationship between the above obstruction class for extensions and the symplectic variation of the symplectic foliation induced on $W$.

[159] 2311.17046

Refined BPS structures and topological recursion - the Weber and Whittaker curves

We study properties of the recently established refined topological recursion for some simple spectral curves associated to quadratic differentials. We prove explicit formulas for the free energy and Voros coefficients of the corresponding quantum curves, and conjecture expressions for all other (smooth) genus zero degree two curves. The results can be written in terms of Bridgeland's notion of refined BPS structure associated to the same initial data, together with a quantum correction to the central charge. The corresponding "invariants" appear to be new, but their interpretation in terms of Donaldson-Thomas theory or QFT is not entirely clear.

[160] 2311.17052

A large-scale particle system with independent jumps and distributed synchronization

We study a system consisting of $n$ particles, moving forward in jumps on the real line. Each particle can make both independent jumps, whose sizes have some distribution, or ``synchronization'' jumps, which allow it to join a randomly chosen other particle if the latter happens to be ahead of it. The mean-field asymptotic regime, where $n\to\infty$, is considered. As $n\to\infty$, we prove the convergence of the system dynamics to that of a deterministic mean-field limit (MFL). We obtain results on the average speed of advance of a ``benchmark'' MFL (BMFL) and the liminf of the steady-state speed of advance, in terms of MFLs that are traveling waves. For the special case of exponentially distributed independent jump sizes, we prove that a traveling wave MFL with speed $v$ exists if and only if $v\ge v_*$, with $v_*$ having simple explicit form; this allows us to show that the average speed of the BMFL is equal to $v_*$ and the liminf of the steady-state speeds is lower bounded by $v_*$. Finally, we put forward a conjecture that both the average speed of the BMFL and the exact limit of the steady-state speeds, under general distribution of an independent jump size, are equal to number $v_{**}$, which is easily found from a ``minimum speed principle.'' This general conjecture is consistent with our results for the exponentially distributed jumps and is confirmed by simulations.

[161] 2311.16110

Community Battery Energy Storage Systems for Enhancing Distribution System Operation: A Multi-objective Optimization Approach

The growing penetration of distributed energy resources (DERs) in distribution networks (DNs) raises new operational challenges, particularly in terms of reliability and voltage regulation. In response to these challenges, we introduce an innovative DN operation framework with multi-objective optimization, leveraging community battery energy storage systems (C-BESS). The proposed framework targets two key operational objectives: first, to minimize voltage deviation, which is a concern for a distribution network service provider (DNSP), and second, to maximize the utilization of DERs on the demand side. Recognizing the conflicting nature of these objectives, we utilize C-BESS to enhance the system's adaptability to dynamically adjust DN operations. The multi-objective optimization problem is solved using the non-dominated sorting genetic algorithm-II (NSGA-II). Case studies using real-world data are conducted to validate the effectiveness of the proposed framework. The results show significant improvements in voltage regulation and DER utilization, demonstrating the potential of C-BESS in enabling more reliable DN operation. Our findings contribute to the ongoing discourse on the role of C-BESS in DN operation enhancement and DER integration.

[162] 2311.16157

GeoTop: Advancing Image Classification with Geometric-Topological Analysis

In this study, we explore the application of Topological Data Analysis (TDA) and Lipschitz-Killing Curvatures (LKCs) as powerful tools for feature extraction and classification in the context of biomedical multiomics problems. TDA allows us to capture topological features and patterns within complex datasets, while LKCs provide essential geometric insights. We investigate the potential of combining both methods to improve classification accuracy. Using a dataset of biomedical images, we demonstrate that TDA and LKCs can effectively extract topological and geometrical features, respectively. The combination of these features results in enhanced classification performance compared to using each method individually. This approach offers promising results and has the potential to advance our understanding of complex biological processes in various biomedical applications. Our findings highlight the value of integrating topological and geometrical information in biomedical data analysis. As we continue to delve into the intricacies of multiomics problems, the fusion of these insights holds great promise for unraveling the underlying biological complexities.

[163] 2311.16224

Defect groups of class $\mathcal{S}$ theories from the Coulomb branch

We study the global forms of class $\mathcal{S}[A_{N-1}]$ 4d $\mathcal{N} = 2$ theories by deriving their defect groups (charges of line operators up to screening by local operators) from Coulomb branch data. Specifically, we employ an explicit construction of the BPS quiver for the case of full regular punctures to show that the defect group is $(\mathbb{Z}_N)^{2g}$, where $g$ is the genus of the associated Riemann surface. This determines a sector of surface operators in the 5d symmetry TFT. We show how these can also be identified from dimensional reduction of M-theory.

[164] 2311.16230

Notes on gauging noninvertible symmetries, part 1: Multiplicity-free cases

In this paper we discuss gauging noninvertible zero-form symmetries in two dimensions. We specialize to certain gaugeable cases, specifically, fusion categories of the form Rep(H) for H a suitable Hopf algebra (which includes the special case Rep(G) for G a finite group). We also specialize to the case that the fusion category is multiplicity-free. We discuss how to construct a modular-invariant partition function from a choice of Frobenius algebra structure on H^*. We discuss how ordinary G orbifolds for finite groups G are a special case of the construction, corresponding to the fusion category Vec(G) = Rep( C[G]^* ). For the cases Rep(S_3), Rep(D_4), and Rep(Q_8), we construct the crossing kernels for general intertwiner maps. We explicitly compute partition functions in the examples of Rep(S_3), Rep(D_4), Rep(Q_8), and Rep(H_8), and discuss applications in c=1 CFTs. We also discuss decomposition in the special case that the entire noninvertible symmetry group acts trivially.

[165] 2311.16252

Mock Modularity In CHL Models

Dabholkar, Murthy and Zagier (DMZ) proved that there is a canonical decomposition of a meromorphic Jacobi form of integral index for $\mathrm{SL}(2, \mathbb{Z})$ with poles on torsion points $z\in\mathbb{Q}\tau+\mathbb{Q}$ into polar and finite parts, and showed that the finite part is a mock Jacobi form. In this paper we generalize the results of DMZ to meromorphic Jacobi forms of rational index for congruence subgroups of $\mathrm{SL}(2, \mathbb{Z})$. As an application, we establish that a large class of single-centered black hole degeneracies in CHL models are given by the Fourier coefficients of mock Jacobi forms. In this process we refine the result of DMZ regarding the set of charges for which the single-centered black hole degeneracies are given by a mock modular form. In particular, in the case studied by DMZ, we present examples of charges for which the single-centered degeneracies are not captured by the mock modular form of the expected index.

[166] 2311.16347

Random generation of group elements using combinatorial group theory and automata theory, along with a hardware example

In this paper, we introduce a novel approach for generating random elements of a finite group given a set of generators of that. Our method draws upon combinatorial group theory and automata theory to achieve this objective. Furthermore, we explore the application of this method in generating random elements of a particularly significant group, namely the symmetric group (or group of permutations on a set). Through rigorous analysis, we demonstrate that our proposed method requires fewer average swaps to generate permutations compared to existing approaches. However, recognizing the need for practical applications, we propose a hardware-based implementation based on our theoretical approach, and provide a comprehensive comparison with previous methods. Our evaluation reveals that our method outperforms existing approaches in certain scenarios. Although our primary proposed method only aims to speed up the shuffling and does not decrease its time complexity, we also extend our method to improve the time complexity.

[167] 2311.16349

Zero Error Correctibility and Phase Retrievability for Twirling Channels

A twirling channel is a quantum channel induced by a continuous unitary representation $\pi = \sum_{i}^{\oplus} m_i\pi_i$, where $\pi_i$ are inequivalent irreducible representations. Motivated by a recent work \cite{Twirling} on minimal mixed unitary rank of $\Phi_{\pi}$, we explore the connections of the independence number, zero error capacity, quantum codes, orthogonality index and phase retrievability of the quantum channel $\Phi_{\pi}$ with the irreducible representation multiplicities $m_i$, the irreducible representation dimensions $\dim H_{\pi_i}$. In particular we show that the independence number of $\Phi_{\pi}$ is the sum of the multiplicities, the orthogonal index of $\Phi_{\pi}$ is exactly the sum of those representation dimensions, and the zero-error capacity is equal to $\log (\sum_{i=1}^{d}m_i)$. We also present a lower bound for the phase retrievability in terms of the minimal length of phase retrievable frames for $C^n$.

[168] 2311.16359

Phase retrievability of frames and quantum channels

A phase retrievable quantum channel refers to a quantum channel $\Phi: B(H_A)\to B(H_B)$ such that there is a positive operator valued measure (POVM) $\{F_{j}\}$ in $B(H_{B})$ and $\{\Phi^*(F_j)\}$ is a phase retrievable operator valued frame. In this paper we examine the phase retrievable quantum channels in terms of their Kraus representations. For quantum channels $\Phi$ of Choi's rank-$2$, we obtain a necessary and sufficient condition under which it is phase retrievable. For the general case, we present several necessary and/or sufficient conditions. In particular, a necessary and sufficient condition is obtained in terms of the relevant matrix-valued joint spectrum of the Kraus operators. Additionally, we also examine, by examples, the problem of constructing quantum channels such that there exists a minimal number of rank-one observables $\{F_{j}\}$ such that $\{\Phi^*(F_j)\}$ does phase retrieval for $H_A$. Conversely, for a given set of rank-one observables $\{F_{j}\}_{j=1}^{N}$, we present a sufficient condition under which, for every $1\leq r\leq N$ given, a phase retrievable quantum channel $\Phi$ of Choi's rank-$r$ can be explicitly constructed.

[169] 2311.16385

A formula for the overlap between Generalized Coherent States of any rank one simple Lie algebra

We provide a formula for computing the overlap between two Generalized Coherent States of any rank one simple Lie algebra. Then, we apply our formula to spin coherent states (i.e. $\mathfrak{su}(2)$ algebra), pseudo-spin coherent states (i.e. $\mathfrak{su}(1,1)$ algebra), and the $\mathfrak{sl}(2,\mathbb{R})$ subalgebras of Virasoro. In all these examples, we show the emergence of a semi-classical behaviour from the set of coherent states and verify that it always happens when some parameter, depending on the algebra and its representation, becomes large.

[170] 2311.16487

On the Robustness of Decision-Focused Learning

Decision-Focused Learning (DFL) is an emerging learning paradigm that tackles the task of training a machine learning (ML) model to predict missing parameters of an incomplete optimization problem, where the missing parameters are predicted. DFL trains an ML model in an end-to-end system, by integrating the prediction and optimization tasks, providing better alignment of the training and testing objectives. DFL has shown a lot of promise and holds the capacity to revolutionize decision-making in many real-world applications. However, very little is known about the performance of these models under adversarial attacks. We adopt ten unique DFL methods and benchmark their performance under two distinctly focused attacks adapted towards the Predict-then-Optimize problem setting. Our study proposes the hypothesis that the robustness of a model is highly correlated with its ability to find predictions that lead to optimal decisions without deviating from the ground-truth label. Furthermore, we provide insight into how to target the models that violate this condition and show how these models respond differently depending on the achieved optimality at the end of their training cycles.

[171] 2311.16519

B-LSTM-MIONet: Bayesian LSTM-based Neural Operators for Learning the Response of Complex Dynamical Systems to Length-Variant Multiple Input Functions

Deep Operator Network (DeepONet) is a neural network framework for learning nonlinear operators such as those from ordinary differential equations (ODEs) describing complex systems. Multiple-input deep neural operators (MIONet) extended DeepONet to allow multiple input functions in different Banach spaces. MIONet offers flexibility in training dataset grid spacing, without constraints on output location. However, it requires offline inputs and cannot handle varying sequence lengths in testing datasets, limiting its real-time application in dynamic complex systems. This work redesigns MIONet, integrating Long Short Term Memory (LSTM) to learn neural operators from time-dependent data. This approach overcomes data discretization constraints and harnesses LSTM's capability with variable-length, real-time data. Factors affecting learning performance, like algorithm extrapolation ability are presented. The framework is enhanced with uncertainty quantification through a novel Bayesian method, sampling from MIONet parameter distributions. Consequently, we develop the B-LSTM-MIONet, incorporating LSTM's temporal strengths with Bayesian robustness, resulting in a more precise and reliable model for noisy datasets.

[172] 2311.16544

Multi-Irreducible Spectral Synchronization for Robust Rotation Averaging

Rotation averaging (RA) is a fundamental problem in robotics and computer vision. In RA, the goal is to estimate a set of $N$ unknown orientations $R_{1}, ..., R_{N} \in SO(3)$, given noisy measurements $R_{ij} \sim R^{-1}_{i} R_{j}$ of a subset of their pairwise relative rotations. This problem is both nonconvex and NP-hard, and thus difficult to solve in the general case. We apply harmonic analysis on compact groups to derive a (convex) spectral relaxation constructed from truncated Fourier decompositions of the individual summands appearing in the RA objective; we then recover an estimate of the RA solution by computing a few extremal eigenpairs of this relaxation, and (approximately) solving a consensus problem. Our approach affords several notable advantages versus prior RA methods: it can be used in conjunction with \emph{any} smooth loss function (including, but not limited to, robust M-estimators), does not require any initialization, and is implemented using only simple (and highly scalable) linear-algebraic computations and parallelizable optimizations over band-limited functions of individual rotational states. Moreover, under the (physically well-motivated) assumption of multiplicative Langevin measurement noise, we derive explicit performance guarantees for our spectral estimator (in the form of probabilistic tail bounds on the estimation error) that are parameterized in terms of graph-theoretic quantities of the underlying measurement network. By concretely linking estimator performance with properties of the underlying measurement graph, our results also indicate how to devise measurement networks that are \emph{guaranteed} to achieve accurate estimation, enabling such downstream tasks as sensor placement, network compression, and active sensing.

[173] 2311.16582

Discretization of Camassa-Holm peakon equation using orthogonal polynomials and matrix $LR$ transformations

Discrete integrable systems are closely related to orthogonal polynomials and isospectral matrix transformations. In this paper, we use these relationships to propose a nonautonomous time-discretization of the Camassa-Holm (CH) peakon equation, which describes the motion of peakon waves, which are soliton waves with sharp peaks. We then validate our time-discretization, and clarify its asymptotic behavior as the discrete-time goes to infinity. We present numerical examples to demonstrate that the proposed discrete equation captures peakon wave motions.

[174] 2311.16686

Algorithmic approach for an unique definition of the next generation matrix

The basic reproduction number R0 is a concept which originated in population dynamics, mathematical epidemiology, and ecology and is closely related to the mean number of children in branching processes.We offer below three new contributions to the literature: 1) We order a universal algorithmic definition of a (F, V) gradient decomposition (and hence of the resulting R0), which requires a minimal input from the user, namely the specification of an admissible set of disease/infection variables. We also present examples where other choices may be more reasonable, with more terms in F, or more terms in V . 2) We glean out from the works of Bacaer a fixed point equation (8) for the extinction probabilities of a stochastic model associated to a deterministic ODE model, which may be expressed in terms of the (F, V ) decomposition. The fact that both R0 and the extinction probabilities are functions of (F, V ) underlines the centrality of this pair, which may be viewed as more fundamental than the famous next generation matrix FV^{-1}. 3) We suggest introducing a new concept of sufficient/minimal disease/infection set (sufficient for determining R0). More precisely, our universal recipe of choosing "new infections" once the "infections" are specified suggests focusing on the choice of the latter, which is also not unique. The maximal choice of choosing all compartments which become 0 at the given boundary point seems to always work, but is the least useful for analytic computations, therefore we propose to investigate the minimal one. As a bonus, this idea seems useful for understanding the Jacobian factorization approach for computing R0 . Last but not least, we offer Mathematica scripts and implement them for a large variety of examples, which illustrate that our recipe others always reasonable results, but that sometimes other reasonable (F, V ) decompositions are available as well.

[175] 2311.16697

Thermal-bioconvection in a non-scattering suspension of phototactic microorganisms

This article investigates the linear stability of thermal-bioconvection within a suspension containing phototactic microorganisms heated from below. In suspension, the upper surface is taken as stress-free, while the lower surface is taken as rigid. The resulting eigenvalue problem, including the bioconvection Rayleigh and thermal Rayleigh numbers, is resolved numerically. Changes in the critical total intensity and Lewis number do not impact the critical threshold of the thermal Rayleigh number; however, they notably influence the critical bioconvection Rayleigh number. The critical total intensity and Lewis number destabilize the suspension. It is observed that heating from below enhances the instability of the layer. At higher temperatures, Rayleigh-B$\acute{e}$nard convection dominates bioconvection, resulting in a single convection cell.

[176] 2311.16706

Sinkhorn Flow: A Continuous-Time Framework for Understanding and Generalizing the Sinkhorn Algorithm

Many problems in machine learning can be formulated as solving entropy-regularized optimal transport on the space of probability measures. The canonical approach involves the Sinkhorn iterates, renowned for their rich mathematical properties. Recently, the Sinkhorn algorithm has been recast within the mirror descent framework, thus benefiting from classical optimization theory insights. Here, we build upon this result by introducing a continuous-time analogue of the Sinkhorn algorithm. This perspective allows us to derive novel variants of Sinkhorn schemes that are robust to noise and bias. Moreover, our continuous-time dynamics not only generalize but also offer a unified perspective on several recently discovered dynamics in machine learning and mathematics, such as the "Wasserstein mirror flow" of (Deb et al. 2023) or the "mean-field Schr\"odinger equation" of (Claisse et al. 2023).

[177] 2311.16760

Fair Interventions in Weighted Congestion Games

In this work we study the power and limitations of fair interventions in weighted congestion games. Specifically, we focus on interventions that aim at improving the equilibrium quality (price of anarchy) and are fair in the sense that identical players receive identical treatment. Within this setting, we provide three key contributions: First, we show that no fair intervention can reduce the price of anarchy below a given factor depending solely on the class of latencies considered. Interestingly, this lower bound is unconditional, i.e., it applies regardless of how much computation interventions are allowed to use. Second, we propose a taxation mechanism that is fair and show that the resulting price of anarchy matches this lower bound, while the mechanism can be efficiently computed in polynomial time. Third, we complement these results by showing that no intervention (fair or not) can achieve a better approximation if polynomial computability is required. We do so by proving that the minimum social cost is NP-hard to approximate below a factor identical to the one previously introduced. In doing so, we also show that the randomized algorithm proposed by Makarychev and Sviridenko (Journal of the ACM, 2018) for the class of optimization problems with a "diseconomy of scale" is optimal, and provide a novel way to derandomize its solution via equilibrium computation.

[178] 2311.16775

Tracking Quintessence

Tracking quintessence in a spatially flat and isotropic space-time, with a minimally coupled canonical scalar field and an asymptotically inverse power-law potential $V(\varphi)\propto\varphi^{-p}$, $p>0$, as $\varphi\rightarrow0$, is investigated by introducing a new three-dimensional \emph{regular} dynamical system. This enables a rigorous explanation of the tracking feature: 1) the dynamical system has a tracker fixed point $\mathrm{T}$ with a two-dimensional stable manifold that pushes an open set of nearby solutions toward a single tracker solution originating from $\mathrm{T}$; 2) all solutions, including the tracker solution and the solutions that track/shadow it, end at a common future attractor fixed point that depends on the potential. Thus, the open set of solutions that shadow the tracker solution share its properties during the tracking quintessence epoch. We also discuss similarities and differences of underlying mechanisms for tracking, thawing and scaling freezing quintessence, and, moreover, we illustrate with state space pictures that all of these types of quintessence exist simultaneously for certain potentials.

[179] 2311.16860

Data-efficient operator learning for solving high Mach number fluid flow problems

We consider the problem of using SciML to predict solutions of high Mach fluid flows over irregular geometries. In this setting, data is limited, and so it is desirable for models to perform well in the low-data setting. We show that Neural Basis Functions (NBF), which learns a basis of behavior modes from the data and then uses this basis to make predictions, is more effective than a basis-unaware baseline model. In addition, we identify continuing challenges in the space of predicting solutions for this type of problem.

[180] 2311.16895

Optimization Theory Based Deep Reinforcement Learning for Resource Allocation in Ultra-Reliable Wireless Networked Control Systems

The design of Wireless Networked Control System (WNCS) requires addressing critical interactions between control and communication systems with minimal complexity and communication overhead while providing ultra-high reliability. This paper introduces a novel optimization theory based deep reinforcement learning (DRL) framework for the joint design of controller and communication systems. The objective of minimum power consumption is targeted while satisfying the schedulability and rate constraints of the communication system in the finite blocklength regime and stability constraint of the control system. Decision variables include the sampling period in the control system, and blocklength and packet error probability in the communication system. The proposed framework contains two stages: optimization theory and DRL. In the optimization theory stage, following the formulation of the joint optimization problem, optimality conditions are derived to find the mathematical relations between the optimal values of the decision variables. These relations allow the decomposition of the problem into multiple building blocks. In the DRL stage, the blocks that are simplified but not tractable are replaced by DRL. Via extensive simulations, the proposed optimization theory based DRL approach is demonstrated to outperform the optimization theory and pure DRL based approaches, with close to optimal performance and much lower complexity.

[181] 2311.16902

Periodic finite-band solutions to the focusing nonlinear Schrödinger equation by the Riemann--Hilbert approach: inverse and direct problems

We consider the Riemann--Hilbert (RH) approach to the construction of periodic finite-band solutions to the focusing nonlinear Schr\"odinger (NLS) equation, addressing the question of how the RH problem parameters can be retrieved from the solution. Within the RH approach, a finite-band solution to the NLS equation is given in terms of the solution of an associated RH problem, the jump conditions for which are characterized by specifying the endpoints of the arcs defining the contour of the RH problem and the constants (so-called phases) involved in the jump matrices. In our work, we solve the problem of retrieving the phases given the solution of the NLS equation evaluated at a fixed time. Our findings are corroborated by numerical examples of phases computation, demonstrating the viability of the method proposed.

[182] 2311.16904

Study of BSM Inter-Packet Gap Tails in C-V2X Networks

Cellular vehicle-to-everything (C-V2X) enables safety-critical connected vehicular service by exchanging basic safety messages (BSMs) among nearby vehicular users (VUEs). Timely transmission of BSMs is crucial to avoid stale information at VUEs. However, successive packet losses can lead to large inter-packet gaps (IPGs), reducing the BSMs' reliability. This paper investigates the tail behavior of IPG and information age (IA) distributions in C-V2X mode 4, a decentralized resource allocation method based on semi-persistent scheduling (SPS). We study the improvements and trade-offs introduced by SAE one-shot transmission to decrease the number of successive BSM losses at destination VUEs. The study employs high-fidelity system-level simulations that closely follow the SPS process of CV2X mode 4 to evaluate the performance of interleaved one-shot SPS transmissions. The numerical results demonstrate significant improvement in the IPG and IA tail distributions in various simulation scenarios. Additionally, we propose an accurate analytical model to characterize the IPG tail behavior of C-V2X BSM transmissions. The proposed model is validated by comparing its results with those obtained using the system-level simulations. Our validation shows that the proposed model generates analytical results that coincide with the asymptotic slopes of IPG distribution in different BSM transmission modes.

[183] 2311.16983

HARQ Retransmissions in C-V2X: A BSM Latency Analysis

Cellular vehicular-to-everything (C-V2X) systems offer the potential for improving road safety, in part through the exchange of periodic basic safety messages (BSMs) between nearby vehicles. The reliability and latency of these messages is a key metric. Hybrid automatic repeat request (HARQ) retransmissions are one technique used to this end. However, HARQ may come at the expense of consuming the limited available wireless resources, especially in highly congested scenarios. This paper studies BSM transmission latency and reliability when HARQ retransmissions are used with the semi-persistent scheduling (SPS) in C-V2X transmission mode 4. We do so through extensive system-level simulations that closely follow the SPS process. Furthermore, we provide an analytical model for the tail behavior of the BSM latency distribution with HARQ retransmissions that is a good approximation to the simulation results. Our study reveals the impact of several deployment settings (e.g., bandwidth configurations and vehicle density).

[184] 2311.16992

Nested Integrals and Rationalizing Transformations

A brief overview of some computer algebra methods for computations with nested integrals is given. The focus is on nested integrals over integrands involving square roots. Rewrite rules for conversion to and from associated nested sums are discussed. We also include a short discussion comparing the holonomic systems approach and the differential field approach. For simplification to rational integrands, we give a comprehensive list of univariate rationalizing transformations, including transformations tuned to map the interval $[0,1]$ bijectively to itself.

[185] 2311.16994

From Snyder space-times to doubly $κ$-deformed Yang quantum phase spaces and their generalizations

We propose the double $\kappa$-deformation of Yang quantum phase space which is described by the generalization of $D=4$ Yang model. We postulate that the algebra of such a model is covariant under the generalized Born map, what permits to derive our model from the $\kappa$-deformed Snyder model. Our generalized quantum phase space depends on five deformation parameters defining two Born map-related dimension-full pairs: $(M, R)$ specifying the Yang model and $(\kappa, \tilde{\kappa})$ characterizing the Born-dual $\kappa$-deformations of quantum space-time and quantum fourmomenta sectors; fifth dimensionless parameter $\rho$ is Born-selfdual. Finally, we define the Kaluza-Klein generalization of the Yang model with Lorentz covariance supplemented by internal $\hat{o}(2N)$ symmetries.

[186] 2311.17007

Computational Hypergraph Discovery, a Gaussian Process framework for connecting the dots

Most scientific challenges can be framed into one of the following three levels of complexity of function approximation. Type 1: Approximate an unknown function given input/output data. Type 2: Consider a collection of variables and functions, some of which are unknown, indexed by the nodes and hyperedges of a hypergraph (a generalized graph where edges can connect more than two vertices). Given partial observations of the variables of the hypergraph (satisfying the functional dependencies imposed by its structure), approximate all the unobserved variables and unknown functions. Type 3: Expanding on Type 2, if the hypergraph structure itself is unknown, use partial observations of the variables of the hypergraph to discover its structure and approximate its unknown functions. While most Computational Science and Engineering and Scientific Machine Learning challenges can be framed as Type 1 and Type 2 problems, many scientific problems can only be categorized as Type 3. Despite their prevalence, these Type 3 challenges have been largely overlooked due to their inherent complexity. Although Gaussian Process (GP) methods are sometimes perceived as well-founded but old technology limited to Type 1 curve fitting, their scope has recently been expanded to Type 2 problems. In this paper, we introduce an interpretable GP framework for Type 3 problems, targeting the data-driven discovery and completion of computational hypergraphs. Our approach is based on a kernel generalization of Row Echelon Form reduction from linear systems to nonlinear ones and variance-based analysis. Here, variables are linked via GPs and those contributing to the highest data variance unveil the hypergraph's structure. We illustrate the scope and efficiency of the proposed approach with applications to (algebraic) equation discovery, network discovery (gene pathways, chemical, and mechanical) and raw data analysis.

[187] 2311.17011

Pricing and hedging for a sticky diffusion

We consider a financial market model featuring a risky asset with a sticky geometric Brownian motion price dynamic and a constant interest rate $r \in \mathbb R$. We prove that the model is arbitrage-free if and only if $r =0 $. In this instance, we find the unique riskless replication strategy and derive the associated pricing equation. Last, we numerically evaluate discrete-time hedging error and error from model mismatch.

[188] 2311.17012

Counter-terrorism in cyber-physical spaces: Best practices and technologies from the state of the art

Context: The demand for protection and security of physical spaces and urban areas increased with the escalation of terroristic attacks in recent years. We envision with the proposed cyber-physical systems and spaces, a city that would indeed become a smarter urbanistic object, proactively providing alerts and being protective against any threat. Objectives: This survey intend to provide a systematic multivocal literature survey comprised of an updated, comprehensive and timely overview of state of the art in counter-terrorism cyber-physical systems, hence aimed at the protection of cyber-physical spaces. Hence, provide guidelines to law enforcement agencies and practitioners providing a description of technologies and best practices for the protection of public spaces. Methods: We analyzed 112 papers collected from different online sources, both from the academic field and from websites and blogs ranging from 2004 till mid-2022. Results: a) There is no one single bullet-proof solution available for the protection of public spaces. b) From our analysis we found three major active fields for the protection of public spaces: Information Technologies, Architectural approaches, Organizational field. c) While the academic suggest best practices and methodologies for the protection of urban areas, the market did not provide any type of implementation of such suggested approaches, which shows a lack of fertilization between academia and industry. Conclusion: The overall analysis has led us to state that there is no one single solution available, conversely, multiple methods and techniques can be put in place to guarantee safety and security in public spaces. The techniques range from architectural design to rethink the design of public spaces keeping security into account in continuity, to emerging technologies such as AI and predictive surveillance.

[189] 2311.17019

Homogeneous Algebraic Complexity Theory and Algebraic Formulas

We study algebraic complexity classes and their complete polynomials under \emph{homogeneous linear} projections, not just under the usual affine linear projections that were originally introduced by Valiant in 1979. These reductions are weaker yet more natural from a geometric complexity theory (GCT) standpoint, because the corresponding orbit closure formulations do not require the padding of polynomials. We give the \emph{first} complete polynomials for VF, the class of sequences of polynomials that admit small algebraic formulas, under homogeneous linear projections: The sum of the entries of the non-commutative elementary symmetric polynomial in 3 by 3 matrices of homogeneous linear forms. Even simpler variants of the elementary symmetric polynomial are hard for the topological closure of a large subclass of VF: the sum of the entries of the non-commutative elementary symmetric polynomial in 2 by 2 matrices of homogeneous linear forms, and homogeneous variants of the continuant polynomial (Bringmann, Ikenmeyer, Zuiddam, JACM '18). This requires a careful study of circuits with arity-3 product gates.

[190] 2311.17040

Rumors with Changing Credibility

Randomized rumor spreading processes diffuse information on an undirected graph and have been widely studied. In this work, we present a generic framework for analyzing a broad class of such processes on regular graphs. Our analysis is protocol-agnostic, as it only requires the expected proportion of newly informed vertices in each round to be bounded, and a natural negative correlation property. This framework allows us to analyze various protocols, including PUSH, PULL, and PUSH-PULL, thereby extending prior research. Unlike previous work, our framework accommodates message failures at any time $t\geq 0$ with a probability of $1-q(t)$, where the credibility $q(t)$ is any function of time. This enables us to model real-world scenarios in which the transmissibility of rumors may fluctuate, as seen in the spread of ``fake news'' and viruses. Additionally, our framework is sufficiently broad to cover dynamic graphs.

[191] 2311.17044

Gauging Non-Invertible Symmetries: Topological Interfaces and Generalized Orbifold Groupoid in 2d QFT

Gauging is a powerful operation on symmetries in quantum field theory (QFT), as it connects distinct theories and also reveals hidden structures in a given theory. We initiate a systematic investigation of gauging discrete generalized symmetries in two-dimensional QFT. Such symmetries are described by topological defect lines (TDLs) which obey fusion rules that are non-invertible in general. Despite this seemingly exotic feature, all well-known properties in gauging invertible symmetries carry over to this general setting, which greatly enhances both the scope and the power of gauging. This is established by formulating generalized gauging in terms of topological interfaces between QFTs, which explains the physical picture for the mathematical concept of algebra objects and associated module categories over fusion categories that encapsulate the algebraic properties of generalized symmetries and their gaugings. This perspective also provides simple physical derivations of well-known mathematical theorems in category theory from basic axiomatic properties of QFT in the presence of such interfaces. We discuss a bootstrap-type analysis to classify such topological interfaces and thus the possible generalized gaugings and demonstrate the procedure in concrete examples of fusion categories. Moreover we present a number of examples to illustrate generalized gauging and its properties in concrete conformal field theories (CFTs). In particular, we identify the generalized orbifold groupoid that captures the structure of fusion between topological interfaces (equivalently sequential gaugings) as well as a plethora of new self-dualities in CFTs under generalized gaugings.

[192] 2311.17051

Long-time asymptotic series for the Painleve II equation: Riemann-Hilbert approach

We elaborate a systematic way to obtain higher order contributions in the nonlinear steepest descent method for Riemann-Hilbert problem associated with homogeneous Painleve II equation. The problem is reformulated as a matrix factorization problem on two circles and can be solved perturbatively reducing it to finite systems of algebraic linear equations. The method is applied to find explicitly long-time asymptotic behaviour for tau function of Painleve II equation.

[193] 2311.17055

No Representation Rules Them All in Category Discovery

In this paper we tackle the problem of Generalized Category Discovery (GCD). Specifically, given a dataset with labelled and unlabelled images, the task is to cluster all images in the unlabelled subset, whether or not they belong to the labelled categories. Our first contribution is to recognize that most existing GCD benchmarks only contain labels for a single clustering of the data, making it difficult to ascertain whether models are using the available labels to solve the GCD task, or simply solving an unsupervised clustering problem. As such, we present a synthetic dataset, named 'Clevr-4', for category discovery. Clevr-4 contains four equally valid partitions of the data, i.e based on object shape, texture, color or count. To solve the task, models are required to extrapolate the taxonomy specified by the labelled set, rather than simply latching onto a single natural grouping of the data. We use this dataset to demonstrate the limitations of unsupervised clustering in the GCD setting, showing that even very strong unsupervised models fail on Clevr-4. We further use Clevr-4 to examine the weaknesses of existing GCD algorithms, and propose a new method which addresses these shortcomings, leveraging consistent findings from the representation learning literature to do so. Our simple solution, which is based on 'mean teachers' and termed $\mu$GCD, substantially outperforms implemented baselines on Clevr-4. Finally, when we transfer these findings to real data on the challenging Semantic Shift Benchmark (SSB), we find that $\mu$GCD outperforms all prior work, setting a new state-of-the-art. For the project webpage, see