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It is well known that inverse semigroups are closely related to \'etale groupoids. In particular, it has recently been shown that there is a (non-functorial) equivalence between localic \'etale groupoids, on one hand, and complete and…

Category Theory · Mathematics 2012-06-19 M. Clarence Protin , Pedro Resende

Let $\Gamma$ be a subset of $\{0,1,2,...\}$. We show that if $\Gamma$ has `gaps' then the completeness and frame properties of the system $\{t^ke^{2\pi i nt}: n\in\mathbb{Z},k\in\Gamma\}$ differ from those of the classical exponential…

Classical Analysis and ODEs · Mathematics 2023-04-11 Aleksei Kulikov , Alexander Ulanovskii , Ilya Zlotnikov

We use free groups to settle a couple questions about the values of the Pimsner-Popa-Voiculescu modulus of quasidiagonality for a set of operators $\Omega$, denoted by qd$(\Omega)$. Along the way we deduce information about the operator…

Operator Algebras · Mathematics 2016-07-11 Caleb Eckhardt

We study the box dimensions of self-affine sets in $\mathbb{R}^3$ which are generated by a finite collection of generalised permutation matrices. We obtain bounds for the dimensions which hold with very minimal assumptions and give rise to…

Dynamical Systems · Mathematics 2021-07-02 Jonathan M. Fraser , Natalia Jurga

We establish a new category equivalent to compact pospaces, and which extend the equivalence between compact Hausdorff spaces and Gleason spaces. As a corollary of this equivalence, we obtain in particular, that every compact pospace is the…

General Topology · Mathematics 2021-02-25 Laurent De Rudder , Georges Hansoul

By using the links between generalized roundness, negative type inequalities and equivariant Hilbert space compressions, we obtain that the generalized roundness of the usual Cayley graph of finitely generated free groups and free abelian…

Group Theory · Mathematics 2007-05-23 Ghislain Jaudon

For any block of a finite group over an algebraically closed field of characteristic $2$ which has dihedral, semidihedral, or generalized quaternion defect groups, we determine explicitly the decomposition of the associated diagonal…

Representation Theory · Mathematics 2025-09-19 Robert Boltje , Serge Bouc , Deniz Yılmaz

In this paper, we give a new approach to the theory of strictly positive kernels. Our method is based on the structure of Fock spaces. As its applications, various examples of strictly positive kernels are given. Moreover, we give a new…

Functional Analysis · Mathematics 2022-09-28 Michio Seto

Given an algebraic torus action on a normal projective variety with finitely generated total coordinate ring, we study the GIT-equivalence for not necessarily ample linearized divisors, and we provide a combinatorial description of the…

Algebraic Geometry · Mathematics 2007-05-23 Florian Berchtold , Juergen Hausen

We prove that the number of cyclically symmetric, self-complementary plane partitions contained in a cube of side $2n$ equals the square of the number of totally symmetric, self-complementary plane partitions contained in the same cube,…

Combinatorics · Mathematics 2007-05-23 Mihai Ciucu

A fair sack is a finite set of independent dice, not required to be fair and allowed to have any number of sides, for which all totals are equally likely. These have been studied for over 60 years. Most results restrict the possible orders…

Probability · Mathematics 2017-07-05 Ian Morrison

Let $G$ be a group. We can topologize the spaces of left-orderings $LO(G)$ and bi-orderings $O(G)$ of $G$ with the product topology. These spaces may or may not have isolated points. It is known that $LO(F_n)$ has no isolated points, where…

Group Theory · Mathematics 2023-04-12 Serhii Dovhyi , Kyrylo Muliarchyk

In this paper, we consider an equivalence relation within the class of finitely presented discrete groups attending to their asymptotic topology rather than their asymptotic geometry. More precisely, we say that two finitely presented…

Geometric Topology · Mathematics 2020-02-05 M. Cárdenas , F. F. Lasheras , A. Quintero , R. Roy

Sacerdote [Sa] has shown that the non-Abelian free groups satisfy precisely the same universal-existential sentences Th(F$_2$)$\cap \forall \exists $ in a first-order language L$_o$ appropriate for group theory. It is shown that in every…

Group Theory · Mathematics 2009-09-25 Anthony Gaglione , Dennis Spellman

We establish Rezk completion functors for $\Theta_n$-spaces with respect to each and all of the completeness conditions. As a consequence, we obtain a characterization completeness of Segal $\Theta_n$-spaces as locality with respect to…

Category Theory · Mathematics 2026-03-30 Miika Tuominen

Sidon spaces have been introduced by Bachoc, Serra and Z\'emor in 2017 as the $q$-analogue of Sidon sets. The interest on Sidon spaces has increased quickly, especially after the work of Roth, Raviv and Tamo in 2018, in which they…

Combinatorics · Mathematics 2023-03-31 Chiara Castello , Olga Polverino , Paolo Santonastaso , Ferdinando Zullo

We consider the long-standing question of whether every regular LB-space is complete. This problem has been open since the 1950s and originates in Grothendieck's early work in functional analysis. Rather than seeking a direct proof or…

Functional Analysis · Mathematics 2026-04-28 Sven-Ake Wegner

This paper is one of a series of papers on coherent spaces and their applications, defined in the recent book 'Coherent Quantum Mechanics' by the first author. The paper studies coherent quantization -- the way operators in the quantum…

Mathematical Physics · Physics 2022-02-08 Arnold Neumaier , Arash Ghaani Farashahi

There is a large literature on cover-free families of finite sets, because of their many applications in combinatorial group testing, cryptographic and communications. This work studies the generalization of cover-free families from sets to…

Combinatorics · Mathematics 2024-07-31 Yunjing Shan , Junling Zhou

It is known that any covering space of a topological group has the natural structure of a topological group. This article discusses a noncommutative generalization of this fact. A noncommutative generalization of the topological group is a…

Operator Algebras · Mathematics 2017-05-31 Petr R. Ivankov