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Lie Groups are Groups that are additionally smooth manifolds such that the multiplication and the inverse maps are smooth.

5 votes

$H_2$ of a simply connected Lie group vanishes

One way to do this is to use a very nice theorem of Weingram: if $G$ is finitely generated, then no nontrivial map $\Omega S^{2n+1} \to K(G, 2n)$ can factor through a finite-dimensional CW complex. …
Jeff Strom's user avatar
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1 vote

Compact Lie group action on non-Hausdorff (but CGWH) space with Hausdorff quotient

How about $X=\{ a,b,x,y\}$ with nontrivial open sets $\{a,b\}$ and $\{ x,y\}$ and $G= Z/2$, discrete. The action exchanges $a$ with $ b$ and $x$ with $y$.
Jeff Strom's user avatar
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13 votes
2 answers
3k views

Left and right eigenvalues

A quaternionic matrix $A$ gives rise to a function $\mathbb{H}^n \to \mathbb{H}^n$ given by $x \mapsto A \cdot x$. This is real linear, but not complex- or quaternionic-linear (in general) if we co …
Jeff Strom's user avatar
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