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Almost sure convergence of differentially positive systems on a globally orderable manifold
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arxiv.org
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1 month ago
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eng
arXiv:2410.11895v3 Announce Type: replace Abstract: Differentially positive systems are nonlinear systems whose linearization along trajectories preserves a cone field on a smooth Riemannian manifold. The structures of cone field come from general relativity and Lie theory. We prove that on a globally orderable manifold, the set of convergent points has full Riemann-Lebesgue measure, thus establishing almost sure convergence. This result t..
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Multiparameter Quantum Supergroups, Deformations and Specializations
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arxiv.org
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1 month ago
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eng
arXiv:2410.22549v2 Announce Type: replace Abstract: In this paper we introduce a multiparameter version of the quantum universal enveloping superalgebras introduced by Yamane in [H. Yamane, "Quantized enveloping algebras associated to simple Lie superalgebras and their universal $R$-matrices", Publ. Res. Inst. Math. Sci. 30 (1994), no. 1, 15-87]. For these objects we consider: - (1) their deformations by twist and by 2-cocycle (both of "t..
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Refined $L^p$ restriction estimate for eigenfunctions on Riemannian surfaces
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arxiv.org
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1 month ago
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eng
arXiv:2411.01577v2 Announce Type: replace Abstract: We refine the $L^p$ restriction estimates for Laplace eigenfunctions on a Riemannian surface, originally established by Burq, G\'erard, and Tzvetkov. First, we establish estimates for the restriction of eigenfunctions to arbitrary Borel sets on the surface, following the formulation of Eswarathasan and Pramanik. We achieve this by proving a variable coefficient version of a weighted Fouri..
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arXiv:2411.03383v3 Announce Type: replace Abstract: How hard is it to estimate a discrete-time signal $(x_{1}, ..., x_{n}) \in \mathbb{C}^n$ satisfying an unknown linear recurrence relation of order $s$ and observed in i.i.d. complex Gaussian noise? The class of all such signals is parametric but extremely rich: it contains all exponential polynomials over $\mathbb{C}$ with total degree $s$, including harmonic oscillations with $s$ arbitra....
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Solver-in-the-Loop joint operator learning: fractional Laplace-Beltrami features for interface reconstruction
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arxiv.org
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1 month ago
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eng
arXiv:2411.05341v2 Announce Type: replace Abstract: In this work, we propose a joint operator learning method for reconstructing images of conductivity coefficients from boundary data. Inspired by the idea of employing partial differential equation (PDE) solvers as preconditioners for this inverse problem, we investigate a ``solver-in-the-loop'' training mechanism. It allows the interaction of learnable parameters integrated in a PDE solve....
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The constructive inverse Galois problem via Hilbert modular forms: realizing the transitive group 17T7
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arxiv.org
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1 month ago
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eng
arXiv:2411.07857v4 Announce Type: replace Abstract: We show how Hilbert modular forms can be used in the constructive inverse Galois problem over the rationals. In particular, we prove that the transitive permutation group 17T7, isomorphic to a split extension of C_2 by PSL_2(FF_16), is a Galois group over the rationals and exhibit an explicit degree 17 polynomial with this Galois group. The group arises from the field of definition of the..
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Stochastic Optimal Linear Quadratic Regulation Control of Discrete-time Systems with Delay and Quadratic Constraints
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arxiv.org
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1 month ago
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eng
arXiv:2411.10795v2 Announce Type: replace Abstract: This article explores the discrete-time stochastic optimal LQR control with delay and quadratic constraints. The inclusion of delay, compared to delay-free optimal LQR control with quadratic constraints, significantly increases the complexity of the problem. Using Lagrangian duality, the optimal control is obtained by solving the Riccati-ZXL equation in conjunction with a gradient ascent ..
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The Polymatroid Representation of a Greedoid, and Associated Galois Connections
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arxiv.org
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1 month ago
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eng
arXiv:2411.15363v4 Announce Type: replace Abstract: A greedoid is a generalization of a matroid allowing for more flexible analyses and modeling of combinatorial optimization problems. However, these structures decimate many matroid properties contributing to their pervasive nature. A polymatroid greedoid [KL85] presents an interesting middle ground, so we further develop this class. First we prove every local poset greedoid for which the ....
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Wonderful Compactification of a Cartan Subalgebra of a Semisimple Lie Algebra
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arxiv.org
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1 month ago
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eng
arXiv:2411.19936v3 Announce Type: replace Abstract: Let $\mathfrak h$ be a Cartan subalgebra of a complex semisimple Lie algebra $\mathfrak g.$ We define a compactification $\bar {\mathfrak h}$ of $\mathfrak h$, which is analogous to the closure $\bar H$ of the corresponding maximal torus $H$ in the adjoint group of $\mathfrak g$ in its wonderful compactification, which was introduced and studied by De Concini and Procesi \cite{DCP}. We ob....
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Acceleration by Random Stepsizes: Hedging, Equalization, and the Arcsine Stepsize Schedule
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arxiv.org
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1 month ago
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eng
arXiv:2412.05790v2 Announce Type: replace Abstract: We show that for separable convex optimization, random stepsizes fully accelerate Gradient Descent. Specifically, using inverse stepsizes i.i.d. from the Arcsine distribution improves the convergence rate from $O(k)$ to $O(\sqrt{k})$, where $k$ is the condition number. No momentum or other algorithmic modifications are required. Our starting point is a remarkable "equalization property" o..
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On the role of semismoothness in the implicit programming approach to selected nonsmooth optimization problems
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arxiv.org
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1 month ago
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eng
arXiv:2412.05953v2 Announce Type: replace Abstract: The paper deals with the implicit programming approach to a class of Mathematical Programs with Equilibrium Constraints (MPECs) and bilevel programs in the case when the corresponding reduced problems are solved using a bundle method of nonsmooth optimization. The obtained results allow us to supply the bundle algorithm with suitable, easily computable ``pseudosubgradients'', ensuring con..
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Highest Posterior Density Intervals of Unimodal Distributions As Analogues to Profile Likelihood Ratio Confidence Intervals
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arxiv.org
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1 month ago
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eng
arXiv:2412.06528v5 Announce Type: replace Abstract: In Bayesian statistics, the highest posterior density (HPD) interval is often used to describe properties of a posterior distribution. As a method for estimating confidence intervals (CIs), the HPD has two main desirable properties. Firstly, it is the shortest interval to have a specified coverage probability. Secondly, every point inside the HPD interval has a density greater than every ..
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arXiv:2412.11086v3 Announce Type: replace Abstract: We study the behavior of perturbations in a compressible one-dimensional inviscid gas with an ambient state consisting of constant pressure and periodically-varying density. We show through asymptotic analysis that long-wavelength perturbations approximately obey a system of dispersive nonlinear wave equations. Computational experiments demonstrate that solutions of the 1D Euler equations..
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Rellich type theorem and unique continuation property for discrete Maxwell operators
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arxiv.org
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1 month ago
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eng
arXiv:2412.11568v2 Announce Type: replace Abstract: We study the Rellich type theorem (RT) for the Maxwell operator __ D = D____0 on Z3 in a constant anisotropic medium, i.e., the permittivity and permeability of which are constant non-scalar diagonal matrices. We also prove the unique continuation property (UCP) in the exterior of a compact convex set Kint $\subset$ Z3 for the perturbed Maxwell operator __ Dp = D__p __0 on Z3 for which th..
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arXiv:2412.11975v4 Announce Type: replace Abstract: The Nielsen-Thomsen sequence plays a pivotal role in refining invariants for C$^*$-algebras beyond the Elliott classification framework. This paper revisits the sequence, introducing the concepts of Nielsen-Thomsen bases, rotation maps and diagonalisable morphisms, to better understand its unnatural splitting. These insights enable novel comparison methods for *-homomorphisms at the level..
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arXiv:2501.00710v2 Announce Type: replace Abstract: Given a triangulated category $\mathcal{C}$, we construct a partial compactification, denoted $\mathcal{A}\mathrm{Stab}(\mathcal{C})$, of the quotient of its stability manifold by $\mathbb{C}$. The purpose of $\mathcal{A}\mathrm{Stab}(\mathcal{C})$ is to shed light on the structure of semiorthogonal decompositions of $\mathcal{C}$. A point of $\mathcal{A}\mathrm{Stab}(\mathcal{C})$, calle....
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Existence of weak solutions for nonlinear drift-diffusion equations with measure data
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arxiv.org
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1 month ago
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eng
arXiv:2501.07847v2 Announce Type: replace Abstract: We consider nonlinear drift-diffusion equations (both porous medium equations and fast diffusion equations) with measure data. We establish the existence of nonnegative weak solutions satisfying gradient estimates, provided that the drift term belongs to a sub-scaling class relevant to the $L^1$ space. When the drift is divergence-free, this requirement can be relaxed: the drift may belon....
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A Min-Max Relation on Dicuts and Dijoins in Weighted Chordal Digraphs
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arxiv.org
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1 month ago
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eng
arXiv:2501.10918v2 Announce Type: replace Abstract: In a digraph, a dicut is a cut where all the arcs cross in one direction. A dijoin is a subset of arcs that intersects every dicut. Edmonds and Giles conjectured that in a weighted digraph, the minimum weight of a dicut is equal to the maximum size of a packing of dijoins. This has been disproved. However, the unweighted version conjectured by Woodall remains open. We prove that the Edmon..
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Kink dynamics for the Yang-Mills field in an extremal Reissner-Nordstr\"om black hole
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arxiv.org
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1 month ago
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eng
arXiv:2501.12790v4 Announce Type: replace Abstract: Considered in this work is the Yang-Mills field in an extremal Reissner-Nordstr\"om black hole, a physically motivated mathematical model introduced by Bizo\'n and Kahl. The kink is a fundamental, strongly unstable stationary solution in this non-perturbative, variable coefficients model, with a polynomial tail and no explicit form. In this paper, we introduce and extend several virial te..
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Stabilization-Free H(curl) and H(div)-Conforming Virtual Element Method
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arxiv.org
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1 month ago
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eng
arXiv:2501.15168v2 Announce Type: replace Abstract: Standard Virtual Element Method (VEM) requires stabilization terms that significantly affect the numerical computation performance. In this work, we propose a stabilization-free VEM for general order \(\mathbf{H}(\operatorname{\mathbf{curl}})\) and \(\mathbf{H}(\operatorname{div})\)-conforming spaces by constructing novel serendipity projectors and corresponding serendipity spaces with mi..
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arXiv:2502.00753v4 Announce Type: replace Abstract: Smoothness is crucial for attaining fast rates in first-order optimization. However, many optimization problems in modern machine learning involve non-smooth objectives. Recent studies relax the smoothness assumption by allowing the Lipschitz constant of the gradient to grow with respect to the gradient norm, which accommodates a broad range of objectives in practice. Despite this progres....
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arXiv:2502.02108v3 Announce Type: replace Abstract: We study the Schur algebra counterpart of a vast class of quantum wreath products. This is achieved by developing a theory of twisted convolution algebras, inspired by geometric intuition. In parallel, we provide an algebraic Schurification via a Kashiwara-Miwa-Stern-type action on a tensor space. We give a uniform proof of Schur duality, and construct explicit bases of the new Schur alge..
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Error estimates for full discretization by an almost mass conservation technique for Cahn--Hilliard systems with dynamic boundary conditions
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arxiv.org
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1 month ago
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eng
arXiv:2502.03847v2 Announce Type: replace Abstract: A proof of optimal-order error estimates is given for the full discretization of the bulk--surface Cahn--Hilliard system with dynamic boundary conditions in a smooth domain. The numerical method combines a linear bulk--surface finite element discretization in space and linearly implicit backward difference formulae of order one to five in time. The error estimates are obtained by a consis..
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arXiv:2503.13157v4 Announce Type: replace Abstract: We introduce and study the notion of ramification ideals in higher ramification theory. After general results on their computation for finite extensions, we discuss their connection with the possibly nontrivial defect of the extensions. We compute them for Artin-Schreier extensions and Kummer extensions of prime degree equal to the residue characteristic, which may or may not have nontriv..
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arXiv:2503.15046v2 Announce Type: replace Abstract: We address the enumeration of Eulerian orientations of 4-valent planar maps according to three parameters: the number of vertices, the number of alternating vertices (having in/out/in/out incident edges), and the number of clockwise oriented faces. This is a refinement of the six vertex model studied by Kostov, then Zinn-Justin and Elvey Price, where one only considers the first two param....
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arXiv:2504.00854v2 Announce Type: replace Abstract: For curves singularities the dimension of smoothing components in the deformation space is an invariant of the singularity, but in general the deformation space has components of different dimensions. We are interested in the question of what the generic singularities are above these components. To this end we revisit the known examples of non-smoothable singularities and study their def....
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Existence, uniqueness and characterisation of vector-valued absolute minimisers for a second order $L^\infty$-variational problem
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arxiv.org
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1 month ago
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eng
arXiv:2504.04181v3 Announce Type: replace Abstract: We study a vectorial $L^\infty$-variational problem of second order, where the supremal functional depends on the vector function $u$ through a linear elliptic operator in divergence form. We prove existence and uniqueness of the minimiser $u_\infty$ under prescribed Dirichlet boundary conditions, together with a characterisation of $u_\infty$ as solution of a specific system of PDEs. Our..
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arXiv:2504.10019v3 Announce Type: replace Abstract: This paper extends the article of the Bruns and Conca on SAGBI bases and their computation (J. Symb. Comput. 120 (2024)) in two directions. (i) We describe the extension of the Singular library sagbiNormaliz.sing to the computation of defining ideals of subalgebras of polynomial rings. (ii) We give a complete classification of the algebras of minors for which the generating set is a SAGBI..
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Diffusion Limits for Measure-Valued Queueing Models, With Application to General Random Order of Service Queues
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arxiv.org
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1 month ago
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eng
arXiv:2504.10633v5 Announce Type: replace Abstract: Currently, there is no general theory for deriving diffusion approximations of queueing systems with high- or infinite-dimensional state descriptors. In this paper, we explore one path for deriving diffusion limit equations of queueing models. The method hinges on a martingale decomposition of dynamics driven by time-changed renewal processes, which are a common feature of many queueing m....
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arXiv:2504.11603v4 Announce Type: replace Abstract: The dynamics of weighted translation operators on Lebesgue spaces, Orlicz spaces, and in general on solid Banach function spaces have been studied in numerous papers. Recently, the dynamics of weighted translations on weighted Orlicz spaces have also been studied by Chen and others. The main idea of this paper is to obtain a generalization of these results to the case of general weighted ..
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arXiv:2504.14455v3 Announce Type: replace Abstract: We extend the topological results of Lytchak-Nagano and Lytchak-Nagano-Stadler for CAT(0) spaces to the setting of Busemann spaces of nonpositive curvature, i.e., BNPC spaces. We give a characterization of locally BNPC topological manifolds in terms of their links and show that the singular set of a locally BNPC homology manifold is discrete. We also prove that any (globally) BNPC topolog..
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Sharp bounds for the $\boldsymbol{p}$-adic $\boldsymbol{n}$-dimensional fractional Hardy operator and a class of integral operators on $\boldsymbol{p}$-adic function spaces
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arxiv.org
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1 month ago
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eng
arXiv:2504.19273v2 Announce Type: replace Abstract: In this paper, we first study the sharp weak estimate for the $p$-adic $n$-dimensional fractional Hardy operator from $L^p$ to $L^{q,\infty}$. Secondly, we study the sharp bounds for the $m$-linear $n$-dimensional $p$-adic integral operator with a kernel on $p$-adic weighted spaces $H_{\alpha}^{\infty}( \mathbb{Q} _{p}^{n} )$. As an application, the sharp bounds for $p$-adic Hardy and Hil..
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arXiv:2504.20549v3 Announce Type: replace Abstract: The Pappas--Rapoport coherence conjecture, proved by Zhu, states that the dimensions of spaces of sections of certain line bundles coincide. The two sides of the equality correspond to line bundles on spherical Schubert varieties in affine Grassmannians and to line bundles on unions of Schubert varieties in affine flag varieties. Algebraically, the claim can be reformulated as an equality..
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Well-posed geometric boundary data in General Relativity, I: Dirichlet boundary data
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arxiv.org
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1 month ago
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eng
arXiv:2505.07128v2 Announce Type: replace Abstract: In this first work in a series, we prove the local-in-time well-posedness of the IBVP for the vacuum Einstein equations with Dirichlet boundary data on a finite timelike boundary, provided the Brown- York stress tensor of the boundary is a Lorentz metric of the same signature (up to an overall sign) as the induced Lorentz metric on the boundary. This is a convexity-type assumption which i..
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Brownian behaviour of the Riemann zeta function around the critical line
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arxiv.org
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1 month ago
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eng
arXiv:2505.07352v2 Announce Type: replace Abstract: We establish a Brownian extension to Selberg's central limit theorem for the Riemann zeta function. This implies various limiting distributions for $\zeta$, including an analogue of the reflection principle for the maximum of the Brownian motion: as $T$ diverges, for any $u>0$ we have \[ \frac{1}{T}\cdot {\rm meas}\Big\{0\leq t\leq T:\max_{\sigma\geq \tfrac{1}{2}}\log|\zeta(\sigma+i t)|\g..
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Tilting equivalence of finite almost derived algebraic cobordism for perfectoid algebras
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arxiv.org
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1 month ago
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eng
arXiv:2505.10809v3 Announce Type: replace Abstract: We prove tilting equivalence for the finite almost derived algebraic cobordism spectrum $\mathrm{dMGL}^{a,fin}$ of perfectoid algebras. More precisely, for any perfectoid algebra, the tilting functor induces a weak equivalence on the corresponding finite almost derived algebraic cobordism spectra. This invariant is a finite-syntomic, derived, and non-$\msthbb{A}^1$-local version of algebr..
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Sharp weak bounds for the Hardy-Littlewood-P\'{o}lya operator and the weak bounds for the multilinear integral operator
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arxiv.org
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1 month ago
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eng
arXiv:2505.17707v2 Announce Type: replace Abstract: In this paper, we first obtain the operator norms of the $n$-dimensional Hardy-Littlewood-P\'{o}lya operator $\mathcal{H}$ from weighted Lebesgue spaces $L^p( \mathbb{R} ^n,| x |^{\beta} ) $ to weighted weak Lebesgue spaces $L^{q,\infty}(\mathbb{R} ^n,|x|^{\gamma})$. Next, we obtain the weak bounds for the $m$-linear $n$-dimensional integral operator.
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arXiv:2505.23293v3 Announce Type: replace Abstract: Mediangle graphs are a common generalization of median graphs (1-sekeleta of CAT(0) cube complexes) and Coxeter graphs (Cayley graphs of Coxeter systems). Answering a question motivated from geometric group theory, we show that these graphs can be endowed with the structure of a contractible cell complex. We further show that the cells of this complex are products of simplices and simplic..
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Higher-dimensional generalization of Youngs' theorem and circular colorings
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arxiv.org
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1 month ago
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eng
arXiv:2505.23562v2 Announce Type: replace Abstract: In 1996, Youngs proved that any quadrangulation of the real projective plane is not 3-chromatic. This result has been extended in various directions over the years, including to other non-orientable closed surfaces, higher-dimensional analogues of quadrangulations and circular colorings. In this paper, we provide a generalization which yields some of these extensions of Youngs' theorem.
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arXiv:2506.01217v2 Announce Type: replace Abstract: We define two stochastic analogs of a geometric flow on even-dimensional manifolds called $Q$-curvature flow, and use the theory of Dirichlet forms to construct weak solutions to both. The first of these flows, which we call the normalized $Q$ flow (NQF), preserves the intrinsic volume normalization from the deterministic setting. The second, which we call the Liouville $Q$ flow (LQF), ha..
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On the heat kernel of a Cayley graph of $\operatorname{PSL}_2\mathbb{Z}$
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arxiv.org
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1 month ago
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eng
arXiv:2506.02340v3 Announce Type: replace Abstract: In this paper, we obtain an explicit formula for the heat kernel on the Cayley graph of the modular group $PSL_2(Z)$, given by the presentation $\langle a,b\mid a^2=1, b^3=1\rangle$. Our approach extends a method of Chung--Yau by observing that the Cayley graph strongly and regularly covers a weighted infinite line. We solve the spectral problem on this line to obtain an integral expressi..
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Asymmetric Perturbation in Solving Bilinear Saddle-Point Optimization
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arxiv.org
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1 month ago
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eng
arXiv:2506.05747v3 Announce Type: replace Abstract: This paper proposes asymmetric perturbation, where only one player's payoff function is perturbed, for solving bilinear saddle-point optimization problems, commonly arising in minimax problems, game theory, and constrained optimization. Symmetric perturbation is known to require decreasing its strength to ensure convergence to a solution, i.e., an equilibrium in the original game, resulti....
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Consistent Infill Estimability of the Regression Slope Between Gaussian Random Fields Under Spatial Confounding
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arxiv.org
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1 month ago
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eng
arXiv:2506.09267v3 Announce Type: replace Abstract: The problem of estimating the slope parameter in regression between two spatial processes under confounding by an unmeasured spatial process has received widespread attention in the recent statistical literature. Yet, a fundamental question remains unresolved: when is this slope consistently estimable under spatial confounding, with existing insights being largely empirical or estimator-s....
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On Effective Banach-Mazur Games and an application to the Poincar\'e Recurrence Theorem for Category
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arxiv.org
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1 month ago
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eng
arXiv:2506.11118v2 Announce Type: replace Abstract: The classical Banach-Mazur game characterizes sets of first category in a topological space. In this work, we show that an effectivized version of the game yields a characterization of sets of effective first category. Using this, we give a proof for the effective Banach Category Theorem. Further, we provide a game-theoretic proof of an effective theorem in dynamical systems, namely the c..
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