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Given a pair of number fields with isomorphic rings of adeles, we construct bijections between objects associated to the pair. For instance we construct an isomorphism of Brauer groups that commutes with restriction. We additionally…

Group Theory · Mathematics 2018-11-14 Benjamin Linowitz , D. B. McReynolds , Nicholas Miller

We show that the dimension of the Cuntz semigroup of a C*-algebra is determined by the dimensions of the Cuntz semigroups of its separable sub-C*-algebras. This allows us to remove separability assumptions from previous results on the…

Operator Algebras · Mathematics 2021-03-25 Hannes Thiel , Eduard Vilalta

On a (pseudo-)Riemannian manifold (M,g), some fields of endomorphisms i.e. sections of End(TM) may be parallel for g. They form an associative algebra A, which is also the commutant of the holonomy group of g. As any associative algebra, A…

Differential Geometry · Mathematics 2022-01-19 Charles Boubel

In this work we reproduce the characterization of $\Gg^s$-sets from the euclidean setting [J. London Math. Soc. 49:267-280,1994] to more general metric spaces. These sets have Hausdorff dimension at least $s$ and are closed by countable…

Metric Geometry · Mathematics 2021-06-10 Felipe Negreira , Emiliano Sequeira

We introduce an equivalence relation on $W^{s,p}({\mathbb S}^N;{\mathbb S}^N)$ involving the topological degree, and we evaluate the distances (in the usual sense and in the Hausdorff sense) between the equivalence classes. In some special…

Functional Analysis · Mathematics 2016-06-16 Haim Brezis , Petru Mironescu , Itai Shafrir

Let $V$ be any vector space of multivariate degree-$d$ homogeneous polynomials with co-dimension at most $k$, and $S$ be the set of points where all polynomials in $V$ {\em nearly} vanish. We establish a qualitatively optimal upper bound on…

Machine Learning · Computer Science 2020-12-15 Ilias Diakonikolas , Daniel M. Kane

Let H denote a semisimple Hopf algebra over an algebraically closed field k of characteristic 0. We show that the degree of any irreducible representation of H whose character belongs to the center of H^* must divide the dimension of H .

Rings and Algebras · Mathematics 2007-05-23 Martin Lorenz

For a Banach space $X$ by $Conv_H(X)$ we denote the space of non-empty closed convex subsets of $X$, endowed with the Hausdorff metric. We prove that for any closed convex set $C\subset X$ and its metric component $H_C=\{A\in…

Functional Analysis · Mathematics 2012-12-19 Taras Banakh , Ivan Hetman

A set $S\subseteq \re^n$ is called to be {\it Semidefinite (SDP)} representable if $S$ equals the projection of a set in higher dimensional space which is describable by some Linear Matrix Inequality (LMI). The contributions of this paper…

Optimization and Control · Mathematics 2008-12-08 J. William Helton , Jiawang Nie

Let ${\sf k}$ be a field, $S$ be a bigraded ${\sf k}$-algebra, and $S_\Delta$ denote the diagonal subalgebra of $S$ corresponding to $\Delta = \{ (cs,es) \; | \; s \in \mathbb{Z} \}$. It is know that the $S_\Delta$ is Koszul for $c,e \gg…

Commutative Algebra · Mathematics 2019-05-21 H. Ananthnarayan , Neeraj Kumar , Vivek Mukundan

We study the local Lipschitz one subsets of a finite dimensional space, that is, sets for which there exists a continuous function whose local Lipschitz derivative is the characteristic function of said set. We give a characterization of a…

Functional Analysis · Mathematics 2026-04-22 Ziemowit M. Wójcicki

We generalize the exact predictive regularity of symmetry groups to give an algebraic theory of patterns, building from a core principle of future equivalence. For topological patterns in fully-discrete one-dimensional systems, future…

Statistical Mechanics · Physics 2023-04-18 Adam Rupe , James P. Crutchfield

A subset $S$ of an integral domain is called a semidomain if the pairs $(S,+)$ and $(S\setminus\{0\}, \cdot)$ are commutative and cancellative semigroups with identities. The multiplication of $S$ extends to the group of differences…

Commutative Algebra · Mathematics 2023-11-30 Hannah Fox , Agastya Goel , Sophia Liao

We study one dimensional sets (Hausdorff dimension) lying in a Hilbert space. The aim is to classify subsets of Hilbert spaces that are contained in a connected set of finite Hausdorff length. We do so by extending and improving results of…

Metric Geometry · Mathematics 2007-05-23 Raanan Schul

We study the Hausdorff dimension of R-analytic subgroups in an R-analytic profinite group, where R is a pro-p ring whose asso- ciated graded ring is an integral domain. In particular, we prove that the set of such Hausdorff dimensions is a…

Group Theory · Mathematics 2016-05-25 Gustavo A. Fernández-Alcober , Eugenio Giannelli , Jon González-Sánchez

Barycentric algebras are an abstraction of the notion of convex sets, defined by a set of equations. We study semitopological and topological barycentric algebras, in the spirit of a previous study by Klaus Keimel on semitopological and…

Functional Analysis · Mathematics 2026-05-22 Jean Goubault-Larrecq

For each nontrivial semisimple Hopf algebra $H$ of dimension sixteen over $\mathbb{C}$, the smallest dimension inner-faithful representation of $H$ acting on a quadratic AS regular algebra $A$ of dimension 2 or 3, homogeneously and…

Rings and Algebras · Mathematics 2022-10-04 Luigi Ferraro , Ellen Kirkman , W. Frank Moore , Robert Won

We introduce the notion of (almost isometric) local retracts in metric space as a natural non-linear version of the concepts of locally complemented and almost isometric ideals from Banach spaces. We prove that given two metric spaces…

Functional Analysis · Mathematics 2023-11-23 Andrés Quilis , Abraham Rueda Zoca

We generalize the notion of analytic/Borel equivalence relations, orbit equivalence relations, and Borel reductions between them to their continuous and quantitative counterparts: analytic/Borel pseudometrics, orbit pseudometrics, and Borel…

Functional Analysis · Mathematics 2023-04-04 Marek Cúth , Michal Doucha , Ondřej Kurka

Let $\mathcal{M}$ be a type II$_1$ von Neumann factor and let $S(\mathcal{M})$ be the associated Murray-von Neumann algebra of all measurable operators affiliated to $\mathcal{M}.$ We extend a result of Kadison and Liu \cite{KL} by showing…

Operator Algebras · Mathematics 2020-01-29 Aleksey Ber , Karimbergen Kudaybergenov , Fedor Sukochev