Equivariant weight filtration for real algebraic varieties with action

Fabien Priziac (1)

1 I2M - Institut de Mathématiques de Marseille

We show the existence of an equivariant weight filtration on the equivariant homology of real algebraic varieties equipped with a finite group action, by applying group homology onto the weight complex of McCrory and Parusi\'nski. The group action enriches the information contained in the induced equivariant weight spectral sequence from which we can not extract finite additivity directly if the group is of even order. Still, we manage to construct additive invariants from its elementary bricks, and prove that they are induced from the very equivariant geometry of real algebraic varieties with action, and that they coincide with Fichou's equivariant virtual Betti numbers in some cases. In the case of the two-elements group, we recover these through the use of globally invariant chains and the equivariant version of Guillén and Navarro Aznar's extension criterion.

Mots clés: equivariant homology; weight filtration; real algebraic varieties; group action; additive invariants

Domaines: Géométrie algébrique [math.AG]

Fabien Priziac. Equivariant weight filtration for real algebraic varieties with action. Journal of the Mathematical Society of Japan, 2016, ⟨10.2969/jmsj/06841789⟩. ⟨hal-00799305v2⟩