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1 vote
1 answer
476 views

Homotopy of group actions

Let $G$ be a topological group and $X$ be a topological space. Let $\alpha$, $\beta:G\times X\to X$ be two group actions. We say that these two actions are homotopic actions if there is a continuous ...
Ali Taghavi's user avatar
3 votes
1 answer
136 views

symmetric group of regular polyhedrons

Let $\Delta^n$ be the regular $n$-simplex spanned by $(n+1)$ vertices, equipped with an Riemannian metric such that all the edges are of equal length. For example, $\Delta^2$: $\Delta^3$: Let $c:=c(...
Shi Q.'s user avatar
  • 543
6 votes
0 answers
426 views

Non invertibility of certain integral arising from group action

Edit 1: According to the comment of Andreas Cap I revise the integral formula in the question. Edit 2: I understand from the following post that some part of the previos version of my question has ...
Ali Taghavi's user avatar
5 votes
1 answer
220 views

Fixed sets of orbit spaces

I've run across something that surprises me, so I'm wondering (1) Is it true? and (2) Is it well known? (And if the answers are affirmative, why didn't I know this already?) Let $G$ be a compact Lie ...
Steve Costenoble's user avatar
4 votes
1 answer
162 views

Representations of Finite Subgroups on Homology

Suppose that $G$ is a connected, simply-connected, complex, semisimple Lie group, and that $H$ is finite subgroup. Consider the left-multiplicative action of $H$ on $G$, and the resulting ...
Peter Crooks's user avatar
  • 4,890
8 votes
1 answer
723 views

Status of Hilbert-Smith conjecture and H-S conjecture for Hölder actions

The Hilbert-Smith conjecture states that If $G$ is a locally compact group which acts effectively on a connected manifold as a topological transformation group then is $G$ a Lie group. It was ...
Zarathustra's user avatar
  • 1,414
21 votes
5 answers
3k views

How to compute the (co)homology of orbit spaces (when the action is not free)?

Suppose a compact Lie group G acts on a compact manifold Q in a not necessarily free manner. Is there any general method to gain information about the quotient Q/G (a stratified space)? For example, I ...
Orbicular's user avatar
  • 211