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We first show that increasing trees are in bijection with set compositions, extending simultaneously a recent result on trees due to Tonks and a classical result on increasing binary trees. We then consider algebraic structures on the…

Combinatorics · Mathematics 2007-05-23 Frederic Patras , Manfred Schocker

We prove that finite groups have the same complex character tables iff the group algebras are twisted forms of each other as Drinfel'd quasi-bialgebras or iff there is non-associative bi-Galois algebra over these groups. The interpretations…

Representation Theory · Mathematics 2007-05-23 A. Davydov

For a quasitriangular C*-quantum group, we enrich the twisted tensor product constructed in the first part of this series to a monoidal structure on the category of its continuous coactions on C*-algebras. We define braided C*-quantum…

Operator Algebras · Mathematics 2024-06-25 Ralf Meyer , Sutanu Roy , Stanisław Lech Woronowicz

Given a Hopf algebra $A$ graded by a discrete group together with an action of the same group preserving the grading, we define a new Hopf algebra, which we call the graded twisting of $A$. If the action is adjoint, this new Hopf algebra is…

Quantum Algebra · Mathematics 2021-06-10 Julien Bichon , Sergey Neshveyev , Makoto Yamashita

We study twisted conjugacy classes of the unit element in different groups. Fel'shtyn and Troitsky showed that the twisted conjugacy class of the unit element of an abelian group is a subgroup for every automorphism. The structure is…

Group Theory · Mathematics 2013-03-07 V. G. Bardakov , T. R. Nasybullov , M. V. Neshchadim

We extend the geometric approach to vertex algebras developed by the first author to twisted modules, allowing us to treat orbifold models in conformal field theory. Let $V$ be a vertex algebra, $H$ a finite group of automorphisms of $V$,…

Algebraic Geometry · Mathematics 2007-05-23 Edward Frenkel , Matthew Szczesny

We describe a special class of representations of an inverse semigroup S on Hilbert's space which we term "tight". These representations are supported on a subset of the spectrum of the idempotent semilattice of S, called the "tight…

Operator Algebras · Mathematics 2008-06-25 Ruy Exel

This paper presents some new Lie groups preserving fixed subspaces of geometric algebras (or Clifford algebras) under the twisted adjoint representation. We consider the cases of subspaces of fixed grades and subspaces determined by the…

Mathematical Physics · Physics 2024-02-06 E. R. Filimoshina , D. S. Shirokov

This note serves as a short and reader-friendly introduction to twisted Brin-Thompson groups, which were recently constructed by Belk and the author to provide a family of simple groups with a variety of interesting properties. Most…

Group Theory · Mathematics 2022-01-04 Matthew C. B. Zaremsky

We introduce a new class of algebras, which we call cluster-tilted. They are by definition the endomorphism algebras of tilting objects in a cluster category. We show that their representation theory is very close to the representation…

Representation Theory · Mathematics 2020-12-21 Aslak Bakke Buan , Bethany Marsh , Idun Reiten

We construct twisting functors for quantum group modules. First over the field $\mathbb{Q}(v)$ but later over any $\mathbb{Z} [v,v^{-1}]$-algebra. The main results in this paper are a rigerous definition of these functors, a proof that they…

Representation Theory · Mathematics 2015-07-24 Dennis Hasselstrøm Pedersen

This paper introduces the notion of twisted toric manifolds which is a generalization of one of symplectic toric manifolds, and proves the weak Delzant type classification theorem for them. The computation methods for their fundamental…

Symplectic Geometry · Mathematics 2007-05-23 Takahiko Yoshida

A general method of investigation of the uniqueness property for $C^*$-algebra equipped with a circle gauge action is discussed. It unifies isomorphism theorems for various crossed products and Cuntz-Krieger uniqueness theorem for…

Operator Algebras · Mathematics 2014-10-10 B. K. Kwasniewski

We develop a theory of operations on the twisted homology of $E_{\infty}$-algebras, generalizing a classical theory developed by J.P. May. First we describe a framework suitable for discussing twisted coefficients, which requires working…

Algebraic Topology · Mathematics 2023-04-04 Calista Bernard

In this paper we suggest a definition for a C*-algebra attached to an injective morphism of some \'Etale groupoid. We take into account all the peculiarities of such objects and present some interesting relations with already well-known…

Operator Algebras · Mathematics 2022-04-22 Bruno Tadeu Costa , Renan Gambale Romano , Felipe Vieira

This is a study of twisted K-theory on a product space $T \times M$. The twisting comes from a decomposable cup product class which applies the 1-cohomology of $T$ and the 2-cohomology of $M$. In the case of a topological product, we give a…

K-Theory and Homology · Mathematics 2014-05-29 Antti J. Harju

We prove that the tensor algebra of a C*-correspondence $X$ is Dirichlet if and only if $X$ is a Hilbert bimodule. As a consequence, we point out and fix an error appearing in the proof of a famous result of Duncan. Secondly we answer a…

Operator Algebras · Mathematics 2014-04-08 Evgenios T. A. Kakariadis

We introduce the notion of twisted generalized complex submanifolds and describe an equivalent characterization in terms of Poisson-Dirac submanifolds. Our characterization recovers a result of Vaisman. An equivalent characterization is…

Differential Geometry · Mathematics 2008-07-21 James Barton , Mathieu Stienon

We show how to compute a certain group of equivalence classes of invariant Drinfeld twists on the algebra of a finite group G over a field k of characteristic zero. This group is naturally isomorphic to the second lazy cohomology group of…

Quantum Algebra · Mathematics 2013-01-17 Pierre Guillot , Christian Kassel

Associative algebras with involution over a field of zero characteristic are considered. It is proved that in this case for any finitely generated associative algebra with involution there exists a finite dimensional algebra with involution…

Rings and Algebras · Mathematics 2013-02-13 Irina Sviridova