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We show how locally smooth actions of compact Lie groups on a manifold $X$ can be used to obtain new upper bounds for the topological complexity $\TC(X)$, in the sense of Farber. We also obtain new bounds for the topological complexity of…

Algebraic Topology · Mathematics 2011-09-27 Mark Grant

We prove that the Euler characteristic of a collapsing Alexandrov space (in particular, a Riemannian manifold) is equal to the sum of the products of the Euler characteristics with compact support of the strata of the limit space and the…

Differential Geometry · Mathematics 2024-12-13 Tadashi Fujioka

In this article we provide a version of the Leray-Serre spectral sequence for equidimensional (i.e. smooth with all orbits of the same dimension) actions of compact connected Lie groups on compact manifolds. The main part of this article…

Algebraic Topology · Mathematics 2025-10-24 Paweł Raźny

We prove that when Hodge theory survives on non-compact symplectic manifolds, a compact symplectic Lie group action having fixed points is necessarily Hamiltonian, provided the associated almost complex structure preserves the space of…

Symplectic Geometry · Mathematics 2015-03-17 Alvaro Pelayo , Tudor S. Ratiu

We classify those manifolds of positive euler characteristic on which a lie group G acts with cohomogeneity one, where G is classical simple

Differential Geometry · Mathematics 2012-10-26 Philipp Frank

The coadjoint orbits of compact Lie groups each carry a canonical (positive definite) K\"ahler structure, famously used to realize the group's irreducible representations in holomorphic sections of appropriate line bundles (Borel-Weil…

Differential Geometry · Mathematics 2022-11-30 Thomas Mason , Francois Ziegler

For a possibly singular complex variety $X$, generating functions of total "orbifold Chern homology classes" of symmetric products $S^nX$ are given. Those are very natural "Chern class versions" (in the sense of Schwartz-MacPherson) of…

Algebraic Geometry · Mathematics 2010-04-01 Toru Ohmoto

This paper identifies the homotopy theories of topological stacks and orbispaces with unstable global homotopy theory. At the same time, we provide a new perspective by interpreting it as the homotopy theory of `spaces with an action of the…

Algebraic Topology · Mathematics 2020-01-13 Stefan Schwede

Let G denote a compact connected Lie group with torsion-free fundamental group acting on a compact space X such that all the isotropy subgroups are connected subgroups of maximal rank. Let $T\subset G$ be a maximal torus with Weyl group W.…

Algebraic Topology · Mathematics 2014-02-26 Alejandro Adem , José Manuel Gómez

In this paper we introduce and study the Euler characteristic associated with algebraic modules generated by arbitrary elements of certain noncommutative polyballs. We provide several asymptotic formulas and prove some of its basic…

Functional Analysis · Mathematics 2014-12-05 Gelu Popescu

We consider twisted equivariant K--theory for actions of a compact Lie group $G$ on a space $X$ where all the isotropy subgroups are connected and of maximal rank. We show that the associated rational spectral sequence \`a la Segal has a…

Algebraic Topology · Mathematics 2019-10-01 Alejandro Adem , José Cantarero , José Manuel Gómez

We determine the equivariant Euler characteristics for the action of a finite symplectic group on its building.

Combinatorics · Mathematics 2020-03-19 Jesper Michael Møller

Based on the Euler-Lagrange cohomology groups $H_{EL}^{(2k-1)}({\cal M}^{2n}) (1 \leqslant k\leqslant n)$ on symplectic manifold $({\cal M}^{2n}, \omega)$, their properties and a kind of classification of vector fields on the manifold, we…

Mathematical Physics · Physics 2007-05-23 Han-Ying Guo , Jianzhong Pan , Bin Zhou

In 2002 R. Suter identified a dihedral symmetry on certain order ideals in Young's lattice and gave a combinatorial action on the partitions in these order ideals. Viewing this result geometrically, the order ideals can be seen to be seen…

Combinatorics · Mathematics 2014-10-09 Chris Berg , Nathan Williams , Mike Zabrocki

A closed form formula (generating function) for the Euler characteristic of the configuration space of $\scriptstyle n$ particles in a simplicial complex is given.

General Topology · Mathematics 2010-03-15 S. R. Gal

We consider actions of reductive complex Lie groups $G=K^C$ on K\"ahler manifolds $X$ such that the $K$--action is Hamiltonian and prove then that the closures of the $G$--orbits are complex-analytic in $X$. This is used to characterize…

Complex Variables · Mathematics 2012-11-15 Bruce Gilligan , Christian Miebach , Karl Oeljeklaus

We study actions by lattices in higher-rank (semi)simple Lie groups on compact manifolds. By classifying certain measures invariant under a related higher-rank abelian action (the diagonal action on the suspension space) we deduce a number…

Dynamical Systems · Mathematics 2024-06-04 Aaron Brown , Federico Rodriguez Hertz , Zhiren Wang

We establish a necessary and sufficient condition for an action of a lattice by homeomorphisms of the circle to extend continuously to the ambient locally compact group. This condition is expressed in terms of the real bounded Euler class…

Group Theory · Mathematics 2009-05-04 Marc Burger

We establish the Hao-Ng isomorphism for generalized gauge actions of locally compact abelian groups on product systems over abelian lattice orders and we then use it to explore Takai duality in this context. As an application we generalize…

Operator Algebras · Mathematics 2019-11-28 Elias Katsoulis

In this paper we characterize the quotients $ X = T/G$ of a complex torus $T$ by the action of a finite group $G$ as the K\"ahler orbifold classifying spaces of the even Euclidean cristallographic groups $\Gamma$, and we prove other similar…

Algebraic Geometry · Mathematics 2024-03-12 Fabrizio Catanese