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The notion of quasicrossed product is introduced in the setting of G-graded quasialgebras, i.e., algebras endowed with a grading by a group G, satisfying a "quasiassociative" law. The equivalence between quasicrossed products and…

Rings and Algebras · Mathematics 2014-12-01 Helena Albuquerque , Elisabete Barreiro , José M. Sánchez-Delgado

We develop a theory of crossed products by "actions" of Hecke pairs $(G, \Gamma)$, motivated by applications in non-abelian $C^*$-duality. Our approach gives back the usual crossed product construction whenever $G / \Gamma$ is a group and…

Operator Algebras · Mathematics 2012-12-27 Rui Palma

A generalization of the 4d Chern-Simons theory action introduced by Costello and Yamazaki is presented. We apply general arguments from symplectic geometry concerning the Hamiltonian action of a symmetry group on the space of gauge…

High Energy Physics - Theory · Physics 2023-11-23 David M. Schmidtt

Cross-connections of normal categories was introduced by K.S.S.Nambooripad while discussing the structure of regular semigroups and via this cross-connections he obtained a beautiful representetion of regualr semigroup called the…

Category Theory · Mathematics 2024-09-10 P. G. Romeo

In this paper we compute the subgroup zeta functions of nilpotent semi-direct products of groups of the form $$G_n=<x_1,...,x_n,y_1,...,y_{n-1}|[x_i,x_n]=y_i, 1\leq i\leq n-1, \text{all other $[,]$ trivial}>$$ and deduce local functional…

Group Theory · Mathematics 2016-09-07 Christopher Voll

Cross-connection theory provides the construction of a semigroup from its ideal structure using small categories. A concordant semigroup is an idempotent-connected abundant semigroup whose idempotents generate a regular subsemigroup. We…

Group Theory · Mathematics 2019-01-25 P. A. Azeef Muhammed , P. G. Romeo , K. S. S. Nambooripad

Semigroup actions and their invertible extensions are discussed. First, we develop a theory of natural extensions for continuous actions of countable, embeddable semigroups. Second, we demonstrate that not every surjective such action of a…

Dynamical Systems · Mathematics 2025-07-14 Raimundo Briceño , Álvaro Bustos-Gajardo , Miguel Donoso-Echenique

We introduce higher order mean curvatures of screen almost conformal (SAC) half-lightlike submanifolds of indefinite contact manifolds, admitting a semi-symmetric non-metric connection, and use them to generalize some known results of [6].…

Differential Geometry · Mathematics 2016-10-25 Fortuné Massamba , Samuel Ssekajja

We show that every finite semilattice can be represented as an atomized semilattice, an algebraic structure with additional elements (atoms) that extend the semilattice's partial order. Each atom maps to one subdirectly irreducible…

Rings and Algebras · Mathematics 2021-02-17 Fernando Martin-Maroto , Gonzalo G. de Polavieja

When a semigroup has a unary operation, it is possible to define two binary operations, namely, left and right division. In addition it is well known that groups can be defined in terms of those two divisions. The aim of this paper is to…

Group Theory · Mathematics 2012-10-01 Joao Araujo , Michael Kinyon

We consider semigroups of transformations (partial mappings defined on a set $A$) closed under the set-theoretic intersection of mappings treated as subsets of $A\times A$. On such semigroups we define two relations: the relation of…

Rings and Algebras · Mathematics 2013-05-28 W. A. Dudek , V. S. Trokhimenko

We introduce the notion of a matched pair of fusion rings and fusion categories, generalizing the one for groups. Using this concept, we define the bicrossed product of fusion rings and fusion categories and we construct exact…

Quantum Algebra · Mathematics 2025-07-09 Monique Müller , Héctor Martín Peña Pollastri , Julia Plavnik

We calculate within a semiclassical approximation the autocorrelation function of cross sections. The starting point is the semiclassical expression for the diagonal matrix elements of an operator. For general operators with a smooth…

Chaotic Dynamics · Physics 2007-08-22 Bruno Eckhardt , Shmuel Fishman , Imre Varga

An inverse semigroup $S$ is a Howson inverse semigroup if the intersection of finitely generated inverse subsemigroups of $S$ is finitely generated. Given a locally finite action $\theta$ of a group $G$ on a semilattice $E$, it is proved…

Group Theory · Mathematics 2014-12-10 Pedro V. Silva , Filipa Soares

Here we carry out computations that help clarify the Lagrangian and Hamiltonian structure of compressible flow. The intent is to be pedagogical and rigorous, providing concrete examples of the theory outlined in Holm, Marsden, and Ratiu…

Mathematical Physics · Physics 2007-05-23 H. S. Bhat

We introduce a formalism of infinite, linearly ordered products in general groups. Using this, we define infinite compositions in certain groups of formal power series such as transseries. We show that such groups can sometimes be…

Group Theory · Mathematics 2025-09-15 Vincent Bagayoko

Morita equivalence of twisted inverse semigroup actions and discrete twisted partial actions are introduced. Morita equivalent actions have Morita equivalent crossed products.

Operator Algebras · Mathematics 2010-10-05 Nandor Sieben

The notions of Busby-Smith and Green type twisted actions are extended to discrete unital inverse semigroups. The connection between the two types, and the connection with twisted partial actions, are investigated. Decomposition theorems…

funct-an · Mathematics 2007-05-23 Nandor Sieben

We decompose the crossed product functor for actions of crossed modules of locally compact groups on C*-algebras into more elementary constructions: taking crossed products by group actions and fibres in C*-algebras over topological spaces.…

Operator Algebras · Mathematics 2015-06-02 Alcides Buss , Ralf Meyer

We introduce a new class of extensions of terms that consists in navigation strategies and insertion of contexts. We introduce an operation of combination on this class which is associative, admits a neutral element and so that each…

Logic in Computer Science · Computer Science 2019-04-25 Walid Belkhir , Nicolas Ratier , Duy Duc Nguyen Michel Lenczner