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For a map f: X -> Y of quasi-compact quasi-separated schemes, we discuss quasi-perfection, that is, the right adjoint f^\times of the derived functor Rf_* respects small direct sums. This is equivalent to the existence of a functorial…

Algebraic Geometry · Mathematics 2011-11-09 Joseph Lipman , Amnon Neeman

We formulate and prove a very general relative version of the Dobrushin-Lanford-Ruelle theorem which gives conditions on constraints of configuration spaces over a finite alphabet such that for every absolutely summable relative…

Mathematical Physics · Physics 2020-05-07 Sebastián Barbieri , Ricardo Gómez , Brian Marcus , Siamak Taati

A quasi-representation of a group is a map from the group into a matrix algebra (or similar object) that approximately satisfies the relations needed to be a representation. Work of many people starting with Kazhdan and Voiculescu, and…

Group Theory · Mathematics 2026-05-25 Rufus Willett

We study how well a real number can be approximated by sums of two or more rational numbers with denominators up to a certain size.

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan , Angel V. Kumchev

How to find "best rational approximations" of maximal commutative subgroups of GL(n,R)? In this paper we pose and make first steps in the study of this problem. It contains both classical problems of Diophantine and simultaneous…

Number Theory · Mathematics 2009-10-20 O. Karpenkov , A. Vershik

Resolving a conjecture of von Neumann, Ogata's theorem in arXiv:1111.5933 showed the highly nontrivial result that arbitrarily many matrices corresponding to macroscopic observables with $N$ sites and a fixed site dimension $d$ are…

Mathematical Physics · Physics 2024-09-24 David Herrera

Let $G$ be a locally compact group with cocompact connected component. We prove that the assembly map from the topological $\k$-theory of $G$ to the $\k$-theory of the reduced $C^*$-algebra of $G$ is an isomorphism.

Operator Algebras · Mathematics 2007-05-23 Jerome Chabert , Siegfried Echterhoff , Ryszard Nest

Let $(\mathcal{G},\nu)$ be a $t$-discrete ergodic groupoid. Consider a finite Von Neumann algebra $\mathcal{M}$ with separable predual. We prove that every uniformly bounded measurable representation $\rho:\mathcal{G} \rightarrow…

Operator Algebras · Mathematics 2025-12-29 Alessio Savini

The main result of this paper is a quasi-hamiltonian analogue of a special case of the O'Shea-Sjamaar convexity theorem for usual momentum maps. We denote by U a simply connected compact connected Lie group and we fix an involutive…

Symplectic Geometry · Mathematics 2007-05-23 Florent Schaffhauser

Toral automorphisms, represented by unimodular integer matrices, are investigated with respect to their symmetries and reversing symmetries. We characterize the symmetry groups of GL(n,Z) matrices with simple spectrum through their…

Dynamical Systems · Mathematics 2019-07-16 Michael Baake , John A. G. Roberts

To a finite dimensional representation of a complex Lie group $G$, an associative algebra of adjoint covariant polynomial maps from the direct sum of $m$ copies of the Lie algebra $\mathfrak{g}$ of $G$ into an algebra of complex matrices is…

Representation Theory · Mathematics 2021-12-14 M. Domokos

We establish a relative version of Gromov's Vanishing Theorem in the presence of amenable open covers with small multiplicity, extending a result of Li, L\"oh, and Moraschini. Our approach relies on Gromov's theory of multicomplexes.

Algebraic Topology · Mathematics 2025-11-20 Pietro Capovilla

We establish inverse and direct theorems on best approximations in quasi-normed Abelian groups through bilateral Bernstein-Jackson inequalities with exact constants. Using integral representations for quasi-norms of functions $f$ in…

Functional Analysis · Mathematics 2024-10-22 Oleh Lopushansky

We study the generalized doubling method for pairs of representations of $G\times GL_k$ where $G$ is a symplectic group, split special orthogonal group or split general spin group. We analyze the poles of the local integrals, and prove that…

Number Theory · Mathematics 2024-05-21 Yuanqing Cai , Solomon Friedberg , Eyal Kaplan

We study approximate equivalence relations up to commensurability, in the presence of a definable measure. As a basic framework, we give a presentation of probability logic based on continuous logic. Hoover's normal form is valid here; if…

Logic · Mathematics 2024-07-30 Ehud Hrushovski

Fix $n \geq 2$ an integer, and let $F$ be a totally real number field. We derive estimates for the finite parts of the $L$-functions of irreducible cuspidal $\operatorname{GL}_n({\bf{A}}_F)$-automorphic representations twisted by class…

Number Theory · Mathematics 2023-11-14 Jeanine Van Order

We propose a new subgradient method for the minimization of nonsmooth convex functions over a convex set. To speed up computations we use adaptive approximate projections only requiring to move within a certain distance of the exact…

Optimization and Control · Mathematics 2015-03-19 Dirk A. Lorenz , Marc E. Pfetsch , Andreas M. Tillmann

We prove the existence of a cuspidal automorphic representation $\pi$ for $GL_{79}/\mathbf{Q}$ of level one and weight zero. We construct $\pi$ using symmetric power functoriality and a change of weight theorem, using Galois deformation…

Number Theory · Mathematics 2024-09-16 George Boxer , Frank Calegari , Toby Gee

The universal approximation theorem asserts that a single hidden layer neural network approximates continuous functions with any desired precision on compact sets. As an existential result, the universal approximation theorem supports the…

Machine Learning · Computer Science 2023-09-15 Wington L. Vital , Guilherme Vieira , Marcos Eduardo Valle

Resolving a conjecture of von Neumann, Ogata's theorem in arXiv:1111.5933 showed the highly nontrivial result that arbitrarily many matrices corresponding to macroscopic observables with $N$ sites and a fixed site dimension $d$ are…

Quantum Physics · Physics 2023-12-06 David Herrera