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5 votes
2 answers
740 views

Equivariant Cohomology of a Complex Projective Variety

Suppose that I have a complex projective variety $X$ endowed with an algebraic action of a complex torus $T$. Suppose also that the set $X^T$ of fixed points is finite. I would like to relate the ...
Peter Crooks's user avatar
  • 4,890
2 votes
1 answer
1k views

Thom-Gysin Sequences and Stratifications

Let $X$ be an affine algebraic variety over $\mathbb{C}$, and let $G$ be a semisimple complex linear algebraic group acting by variety automorphisms with finitely many orbits. The decomposition of $X$ ...
Peter Crooks's user avatar
  • 4,890
5 votes
2 answers
830 views

Stabilizers for nilpotent adjoint orbits of semisimple groups

Let $G$ be a connected, simply-connected, complex, semisimple Lie group with Lie algebra $\frak{g}$. Suppose that $X\in\frak{g}$ is a nilpotent element (i.e. that $ad_X:\frak{g}\rightarrow\frak{g}$ is ...
Peter Crooks's user avatar
  • 4,890
13 votes
4 answers
4k views

Fundamental group of Lie groups

Let $T$ be a torus $V/\Gamma$, $\gamma$ a loop on $T$ based at the origin. Then it is easy to see that $$2 \gamma = \gamma \ast \gamma \in \pi_1(T).$$ Here $2 \gamma$ is obtained by rescaling $\gamma$...
Andrea Ferretti's user avatar
0 votes
1 answer
466 views

Natural embedding GL_n(C) -> C^{n^2} \ {0} induces zero on cohomology

The question looks like an exercise in elementary algebraic topology, but I didn't manage to solve it. I am considering this question because it is a toy example in a problem I'm thinking about. Let'...
Evgeny Shinder's user avatar
8 votes
3 answers
2k views

Cohomology rings of $ GL_n(C)$, $SL_n(C)$

Can anyone provide me with the reference for the following fact (idea of the proof will be appreciated too): Cohomology ring with $\mathbb Q$-coefficients of a group $G$ (I don't know precisely what ...
Evgeny Shinder's user avatar