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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

In this article, we introduce the concept of partial groupoid actions on R- semicategories as well as we give criteria for existence of a globalization of it. This point of view is a generalization of the notions of partial groupoid actions…

Rings and Algebras · Mathematics 2018-11-29 V. Marín , H. Pinedo

The extending structures and unified products for Zinbiel algebras are developed. Some special cases of unified products such as crossed products and matched pair of Zinbiel algebras are studied. It is proved that the extending structures…

Rings and Algebras · Mathematics 2023-01-03 Tao Zhang , Ling Zhang

We investigate the behaviour of split extensions in the category OrdGrp of (pre)\-ordered groups. Namely we show that the lexicographic order plays a key role on the existence of compatible orders for semidirect products, establishing…

Category Theory · Mathematics 2022-12-15 Maria Manuel Clementino , Carla Ruivo

Cup products provide a natural approach to access higher bounded cohomology groups. We extend vanishing results on cup products of Brooks quasimorphisms of free groups to cup products of median quasimorphisms, i.e., Brooks-type…

Group Theory · Mathematics 2025-02-21 Benjamin Brück , Francesco Fournier-Facio , Clara Loeh

We examine crossed product C*-algebras associated with non-minimal free actions of countably infinite discrete abelian groups on the circle, extending the work of Putnam, Schmidt, and Skau. We obtain a large class of unital separable…

Operator Algebras · Mathematics 2026-04-21 Jamie Bell

In this paper, using group actions, we introduce a new method for constructing partial geometric designs (sometimes referred to as $1\frac{1}{2}$-designs). Using this new method, we construct several infinite families of partial geometric…

Combinatorics · Mathematics 2019-04-15 Jerod Michel , Qi Wang

This paper provides a general operadic definition for the notion of splitting the operations of algebraic structures. This construction is proved to be equivalent to some Manin products of operads and it is shown to be closely related to…

Quantum Algebra · Mathematics 2013-02-05 Chengming Bai , Olivia Bellier , Li Guo , Xiang Ni

We investigate the skew-adjoint extensions of a partial derivative operator acting in the direction of one of the sides a unit square. We investigate the unitary equivalence of such extensions and the spectra of such extensions. It follows…

Spectral Theory · Mathematics 2013-01-15 Steen Pedersen , Feng Tian

We introduce the trivial intersection property for concrete operator spaces and we show that a unital space with this property has no nontrivial boundary ideals. We provide various examples of such spaces, among which are strongly reflexive…

Operator Algebras · Mathematics 2025-11-26 Nikolaos Koutsonikos-Kouloumpis

The split involution quantization scheme, proposed previously for pure second--class constraints only, is extended to cover the case of the presence of irreducible first--class constraints. The explicit Sp(2)--symmetry property of the…

High Energy Physics - Theory · Physics 2015-06-26 I. A. Batalin , S. L. Lyakhovich , I. V. Tyutin

The action principle is frequently used to derive the classical equations of motion. The action may also be used to associate group elements with curves in the space-time manifold, similar to the gauge transformations. The action principle…

General Relativity and Quantum Cosmology · Physics 2015-06-25 S. R. Vatsya

We introduce a new notion of twisted actions of inverse semigroups and show that they correspond bijectively to certain regular Fell bundles over inverse semigroups, yielding in this way a structure classification of such bundles. These…

Operator Algebras · Mathematics 2014-02-26 Alcides Buss , Ruy Exel

We classify all non-degenerate skew-hermitian forms defined over certain local rings, not necessarily commutative, and study some of the fundamental properties of the associated unitary groups, including their orders when the ring in…

Rings and Algebras · Mathematics 2018-04-10 J. Cruickshank , F. Szechtman

It this note we investigate the structure of the group of \sigma-unitary units in some noncommutative modular group algebras KG, where \sigma is a non-classical ring involution of KG.

Rings and Algebras · Mathematics 2008-03-04 Victor Bovdi , Tibor Rozgonyi

We extend the definition of Weinstein's Action homomorphism to Hamiltonian actions with equivariant moment maps of (possibly infinite-dimensional) Lie groups on symplectic manifolds, and show that under conditions including a uniform bound…

Symplectic Geometry · Mathematics 2012-02-22 Egor Shelukhin

Recent algorithmic advances in algebraic automata theory drew attention to semigroupoids (semicategories). These are mathematical descriptions of typed computational processes, but they have not been studied systematically in the context of…

Formal Languages and Automata Theory · Computer Science 2025-09-30 Attila Egri-Nagy , Chrystopher L. Nehaniv

We use foliations and connections on principal Lie groupoid bundles to prove various integrability results for Lie algebroids. In particular, we show, under quite general assumptions, that the semi-direct product associated to an…

Differential Geometry · Mathematics 2007-05-23 Ieke Moerdijk , Janez Mrcun

A section of a Riemannian $G$-manifold $M$ is a closed submanifold $\Sigma$ which meets each orbit orthogonally. It is shown that the algebra of $G$-invariant differential forms on $M$ which are horizontal in the sense that they kill every…

dg-ga · Mathematics 2008-02-03 Peter W. Michor

Let $M$ be a monoid, $\mathscr{C}$ a category with pullbacks and $X$ an object of $\mathscr{C}$. We introduce the notion of a partial action $\alpha$ of $M$ on $X$ and study the globalization question for $\alpha$. If $\alpha$ admits a…

Category Theory · Mathematics 2026-02-05 Mykola Khrypchenko , Francisco Klock