Residues in group completions and the Cech cohomology of BG

الأصل · EN

Let G be a connected affine algebraic group over C, G → X be an open immersion of G-varieties, Z = X-G and i: Z → X be the inclusion. Let α∈ H*(G,C) be primitive. We give a method to compute the image of α in H*(Z, i!Cₓ), using a lift of α along the first edge map of the Čech spectral sequence for H*(BG, C). We apply it to the wonderful compactification of a centerless semisimple group G.