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We show that the equivariant cohomology of any hyperpolar action of a compact and connected Lie group on a symmetric space of compact type is a Cohen-Macaulay ring. This generalizes some results previously obtained by the authors.

Differential Geometry · Mathematics 2019-09-23 Oliver Goertsches , Sam Hagh Shenas Noshari , Augustin-Liviu Mare

We introduce a method to study C*-algebras possessing an action of the circle group, from the point of view of its internal structure and its K-theory. Under relatively mild conditions our structure Theorem shows that any C*-algebra, where…

funct-an · Mathematics 2016-08-31 Ruy Exel

In this paper, we study the equivariant homotopy type of a connected sum of linear actions on complex projective planes defined by Hambleton and Tanase. These actions are constructed for cyclic groups of odd order. We construct cellular…

Algebraic Topology · Mathematics 2021-09-28 Samik Basu , Pinka Dey , Aparajita Karmakar

In this paper we consider the action of the mapping class group of a surface on the space of homomorphisms from the fundamental group of a surface into PSL(2,R). Goldman conjectured that when the surface is closed and of genus bigger than…

Geometric Topology · Mathematics 2007-07-23 Panagiota Konstantinou

We define the equivariant Chern-Schwartz-MacPherson class of a possibly singular algebraic variety with a group action over the complex number field (or a field of characteristic 0). In fact, we construct a natural transformation from the…

Algebraic Geometry · Mathematics 2009-11-10 Toru Ohmoto

This is an overview of the idea of a crossed module. For a group, the triple that consists of the group, its group of automorphisms, and the canonical homomorphism from the group to its group of automorphisms constitutes a crossed module.…

Group Theory · Mathematics 2024-03-26 Johannes Huebschmann

We introduce a general definition of a $n$-crossed module of $P$-algebras over an algebraic operad $P$, which coincides with historical definitions in the cases of the operads As and Lie and $n = 1$. We establish a natural isomorphism…

K-Theory and Homology · Mathematics 2025-02-10 Johan Leray , Salim Rivière , Friedrich Wagemann

The aim of this paper is to investigate the homology groups of mathematical models of concurrency. We study the Baues-Wirsching homology groups of a small category associated with a partial monoid action on a set. We prove that these groups…

Algebraic Topology · Mathematics 2011-11-04 Ahmet A. Husainov

We give a general method for computing the cyclic cohomology of crossed products by etale groupoids, extending the Feigin-Tsygan-Nistor spectral sequences. In particular we extend the computations performed by Brylinski, Burghelea,Connes…

funct-an · Mathematics 2007-05-23 Crainic Marius

The paper presents a construction of the crossed product of a C*-algebra by a commutative semigroup of bounded positive linear maps generated by partial isometries. In particular, it generalizes Antonevich, Bakhtin, Lebedev's crossed…

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

Given a proper, cocompact action of a Lie groupoid, we define a higher index pairing between invariant elliptic differential operators and smooth groupoid cohomology classes. We prove a cohomological index formula for this pairing by…

Differential Geometry · Mathematics 2014-06-06 M. J. Pflaum , H. Posthuma , X. Tang

Two actions of the Hecke algebra of type A on the corresponding polynomial ring are studied. Both are deformations of the natural action of the symmetric group on polynomials, and keep symmetric functions invariant. We give an explicit…

Representation Theory · Mathematics 2007-05-23 Ron M. Adin , Alexander Postnikov , Yuval Roichman

This paper introduces a description of Endomorphisms of the translation group in an affine plane, will define the addition and composition of the set of endomorphisms and specify the neutral elements associated with these two actions and…

General Mathematics · Mathematics 2022-08-23 Orgest Zaka

Prolongations of a group extension can be studied in a more general situation that we call group extensions of the co-type of a crossed module. Cohomology classification of such extensions is obtained by applying the obstruction theory of…

Category Theory · Mathematics 2015-03-17 Nguyen Tien Quang

In this paper we will define notion homotopy of morphisms of crossed modules of Lie algebras. Then we construct a groupoid structure of Lie crossed module morphisms and their homotopies.

Category Theory · Mathematics 2016-09-30 I. Ilker Akca , Yavuz Sidal

We present a way of constructing and deforming diffeomorphisms of manifolds endowed with a Lie group action. This is applied to the study of exotic diffeomorphisms and involutions of spheres and to the equivariant homotopy of Lie groups.

Differential Geometry · Mathematics 2007-08-14 C. E. Durán , A. Rigas

We prove a coherence theorem for actions of groups on monoidal categories. As an application we prove coherence for arbitrary braided $G$-crossed categories.

Quantum Algebra · Mathematics 2017-07-14 César Galindo

We prove several completion theorems for equivariant K-theory and cyclic homology of schemes with group action over a field. One of these shows that for an algebraic space over a field acted upon by a linear algebraic group, the derived…

Algebraic Geometry · Mathematics 2025-02-14 Amalendu Krishna , Ritankar Nath

We use symplectic cobordism, and the localization result of Ginzburg, Guillemin, and Karshon, to find a wall-crossing formula for the signature of regular symplectic quotients of Hamiltonian torus actions. The formula is recursive,…

Symplectic Geometry · Mathematics 2007-05-23 David S. Metzler

Pattern-equivariant (PE) cohomology is a well-established tool with which to interpret the \v{C}ech cohomology groups of a tiling space in a highly geometric way. In this paper we consider homology groups of PE infinite chains. We establish…

General Topology · Mathematics 2018-03-16 James J. Walton