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Let F be a field with characteristic two. We generalize the second trace form for central simple algebras with odd degree over F. We determine the second trace form and the Arf invariant and Clifford invariant for tensor products of central…

Number Theory · Mathematics 2007-05-23 A. C. de la Maza

Assuming the existence of $\mathfrak c$ incomparable selective ultrafilters, we classify the non-torsion Abelian groups of cardinality $\mathfrak c$ that admit a countably compact group topology. We show that for each $\kappa \in [\mathfrak…

General Topology · Mathematics 2021-04-26 M. K. Bellini , A. C. Boero , V. O. Rodrigues , A. H. Tomita

Among compact Hausdorff groups G whose maximal profinite quotient is finitely generated, we characterize those that possess a proper dense normal subgroup. We also prove that the abstract commutator subgroup [H,G] is closed for every closed…

Group Theory · Mathematics 2013-10-21 Nikolay Nikolov , Dan Segal

We classify the pairs $(C,G)$ where $C$ is a seminormal curve over an arbitrary field $k$ and $G$ is a smooth connected algebraic group acting faithfully on $C$ with a dense orbit, and we determine the equivariant Picard group of $C$. We…

Algebraic Geometry · Mathematics 2017-03-29 Bruno Laurent

We obtain many results and solve some problems about feebly compact paratopological groups. We obtain necessary and sufficient conditions for such a group to be topological. One of them is the quasiregularity. We prove that each…

Group Theory · Mathematics 2020-08-05 Taras Banakh , Alex Ravsky

The aim of this paper is to present the main constructions of the substructures of an almost groupoid and to discuss their basic properties. The definitions and properties concerning these new algebraic constructions extend to almost…

Group Theory · Mathematics 2026-02-06 Mihai Ivan

In this paper we study left invariant CR structures on Lie groups which are compatible with geometric properties as Poisson and kahler properties.

Differential Geometry · Mathematics 2007-05-23 A. Tsemo

We introduce and investigate using Hilbert modules the properties of the Fourier algebra A(G) for a locally compact groupoid G. We establish a duality theorem for such groupoids in terms of multiplicative module maps. This includes as a…

Operator Algebras · Mathematics 2007-05-23 Alan L. T. Paterson

We show that each local field $\mathbb{F}_q((t))$ of characteristic $p > 0$ is characterised up to isomorphism within the class of all fields of imperfect exponent at most $1$ by (certain small quotients of) its absolute Galois group…

Number Theory · Mathematics 2025-10-15 Philip Dittmann

We use the structure lattice, introduced in Part I, to undertake a systematic study of the class $\mathscr S$ consisting of compactly generated, topologically simple, totally disconnected locally compact groups that are non-discrete. Given…

Group Theory · Mathematics 2017-07-07 Pierre-Emmanuel Caprace , Colin D. Reid , George A. Willis

We address the type I dichotomy for two-step nilpotent locally compact groups. Invoking work of Baggett-Kleppner, we characterize the closed points of the unitary dual of such a group $G$ purely in terms of the group structure. An algebraic…

Representation Theory · Mathematics 2025-10-01 Pierre-Emmanuel Caprace , Max Carter

In this paper, we study the structures of Schur algebra and Lusztig algebra associated to partial flag varieties of affine type D. We show that there is a subalgebra of Lusztig algebra and the quantum groups arising from this subalgebras…

Quantum Algebra · Mathematics 2024-03-08 Quanyong Chen , Zhaobing Fan

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 will present an algebra related to the Coxeter group of type I2n which can be taken as a twisted subalgebra in Brauer algebra of type A_{n-1}. Also we will describe some properties of this algebra.

Representation Theory · Mathematics 2012-07-26 Shoumin Liu

It is a study note detailing the connection between Boolean inverse monoids and ample groupoids.

Rings and Algebras · Mathematics 2026-03-27 Chi-Keung Ng , Rui Tian

We give an example of a locally compact effective Hausdorff, minimal ample groupoid such that its rational homology differs from the $K$-theory of its reduced groupoid $C^*$-algebra. Moreover, we prove that such example satisfies Matui's…

Operator Algebras · Mathematics 2021-04-06 Eduard Ortega , Alvaro Sanchez

Adapting a claim of M. Kracht, we establish a characterization of the typable partial applicative algebras.

Logic · Mathematics 2009-09-30 P. H. Rodenburg , I. Bethke

We study algebraic structures ($L_\infty$ and $A_\infty$-algebras) introduced by Gaiotto, Moore and Witten in their recent work devoted to certain supersymmetric 2-dimensional massive field theories. We show that such structures can be…

Symplectic Geometry · Mathematics 2014-08-14 Mikhail Kapranov , Maxim Kontsevich , Yan Soibelman

In this work we study some properties of comldules over (non-cosemisimple) Hopf algebras possessing integrals, which are also called co-Frobenius Hopf algebras. We apply the result obtained to the classification of representations of…

Quantum Algebra · Mathematics 2007-05-23 Phung Ho Hai

Let $X$ be a second countable locally compact Abelian group. We prove some group analogues of the Skitovich--Darmois, Heyde and Kac--Bernstein characterisation theorems for $Q$-independent random variables taking values in the group $X$.…

Probability · Mathematics 2018-01-08 Margaryta Myronyuk