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Given a partial action $\alpha=(A_g,\alpha_g)_{g\in \mathcal{G}}$ of a connected groupoid $\mathcal{G}$ on a ring $A$ and an object $x$ of $\mathcal{G}$, the isotropy group $\mathcal{G}(x)$ acts partially on the ideal $A_x$ of $A$ by the…

Rings and Algebras · Mathematics 2020-11-18 Dirceu Bagio , Antonio Paques , Héctor Pinedo

In this work, we review some properties of twisted partial actions of Hopf algebras on unital algebras and give necessary and sufficient conditions for a twisted partial action to have a globalization. We also elaborate a series of…

Quantum Algebra · Mathematics 2019-02-20 Marcelo M. S. Alves , Eliezer Batista , Michael Dokuchaev , Antonio Paques

We establish rigidity for partial transformation groupoids associated with algebraic actions of semigroups: If two such groupoids (satisfying appropriate conditions) are isomorphic, then the globalizations of the initial algebraic actions…

Dynamical Systems · Mathematics 2026-04-14 Chris Bruce , Xin Li

In partial action theory, a pertinent question is whenever given a partial (co)action of a Hopf algebra A on an algebra R, it is possible to construct an enveloping (co)action. The authors Alves and Batista, in [2],have shown that this is…

Rings and Algebras · Mathematics 2019-05-07 Eneilson Fontes , Graziela Fonseca , Grasiela Martini

Some basic notions and results in Topological Dynamics are extended to continuous groupoid actions in topological spaces. We focus mainly on recurrence properties. Besides results that are analogous to the classical case of group actions,…

Dynamical Systems · Mathematics 2022-12-01 Felipe Flores , Marius Mantoiu

In this work we investigate partial actions of a Hopf algebra H on nonunital algebras and the associated partial smash products. We show that our partial actions correspond to nonunital algebras in the category of partial representations of…

Rings and Algebras · Mathematics 2022-10-31 Marcelo Muniz Alves , Tiago Luiz Ferrazza

We introduce "geometric" partial comodules over coalgebras in monoidal categories, as an alternative notion to the notion of partial action and coaction of a Hopf algebra introduced by Caenepeel and Janssen. The name is motivated by the…

Rings and Algebras · Mathematics 2019-11-25 Jiawei Hu , Joost Vercruysse

In this paper we introduce the notions of partial bimodule algebra and partial bico- module algebra. We also deal with the existence of globalizations for these structures, generalizing related results appeared in [2, 4]. As an application…

Rings and Algebras · Mathematics 2015-05-20 Felipe Castro , Antonio Paques , Glauber Quadros , Alveri Sant'Ana

A. Bak developed a combinatorial approach to higher $K$-theory, in which control is kept of the elementary operations involved, through paths and `paths of paths' in what he called a global action. The homotopy theory of these was developed…

Algebraic Topology · Mathematics 2007-05-23 A. Bak , R. Brown , G. Minian , T. Porter

We give a length one projective resolution of the trivial module for the groupoid of a semi-saturated partial action (in the sense of Exel) of a free group on a compact Hausdorff and totally disconnected space. As a consequence we obtain an…

Operator Algebras · Mathematics 2026-02-18 Benjamin Steinberg

We develop equivariant KK-theory for locally compact groupoid actions by Morita equivalences on real and complex graded C*-algebras. Functoriality with respect to generalised morphisms and Bott periodicity are discussed. We introduce…

K-Theory and Homology · Mathematics 2013-10-16 El-kaïoum M. Moutuou

We survey the general theory of groupoids, groupoid actions, groupoid principal bundles, and various kinds of morphisms between groupoids in the framework of categories with pretopology. We study extra assumptions on pretopologies that are…

Category Theory · Mathematics 2016-01-26 Ralf Meyer , Chenchang Zhu

Localization is a topological technique that allows us to make global equivariant computations in terms of local data at the fixed points. For example, we may compute a global integral by summing integrals at each of the fixed points. Or,…

Symplectic Geometry · Mathematics 2007-10-30 Tara S. Holm

In this paper, we study isometric actions on finite-dimensional CAT(0) spaces for the Higman-Thompson groups $T_n$, which are generalizations of Thompson's group $T$. It is known that every semi-simple action of $T$ on a complete CAT(0)…

Group Theory · Mathematics 2023-08-25 Motoko Kato

We give a criterion for group elements to have fixed points with respect to a semi-simple action on a complete CAT(0) space of finite topological dimension. As an application, we show that Thompson's group T and various generalizations of…

Group Theory · Mathematics 2020-07-15 Motoko Kato

The effectiveness of the aplication of constructions in $G$-graded $k$-categories to the computation of the fundamental group of a finite dimensional $k$-algebra, alongside with open problems still left untouched by those methods and new…

Rings and Algebras · Mathematics 2012-02-16 Edson R. Alvares , Marcelo M. S. Alves , Eliezer Batista

We give a new characterization of partial groups as a subcategory of symmetric (simplicial) sets. This subcategory has an explicit reflection, which permits one to compute colimits in the category of partial groups. We also introduce the…

Group Theory · Mathematics 2025-03-10 Philip Hackney , Justin Lynd

Partial actions of Hopf algebras can be considered as a generalization of partial actions of groups on algebras. Among important properties of partial Hopf actions, it is possible to assure the existence of enveloping actions. This allows…

Rings and Algebras · Mathematics 2009-10-08 Marcelo Muniz S. Alves , Eliezer Batista

In a previous paper we have constructed a compactification $KGl_n$ of the general linear group $Gl_n$, which in many respects is analogous to the so called wonderful compactification of adjoint semisimple algebraic groups as studied by De…

Algebraic Geometry · Mathematics 2007-05-23 Ivan Kausz

A generalized moment map is proposed for arbitrary symplectic actions of compact connected Lie groups on closed symplectic manifolds, in the spirit of the circle -valued maps introduced by D. McDuff in the case of non-Hamiltonian circle…

Symplectic Geometry · Mathematics 2016-09-07 Pierre Sleewaegen