The periodic cyclic homology of crossed products of finite type algebras

Brodzki Jacek (1) , Dave Shantanu (2) , Victor Nistor (3)

1 University of Southhampton
2 WPI - Wolfgang Pauli Institute
3 IECL - Institut Élie Cartan de Lorraine

We study the periodic cyclic homology groups of the cross-product of a finite type algebra $A$ by a discrete group $\Gamma$. In case $A$ is commutative and $\Gamma$ is finite, our results are complete and given in terms of the singular cohomology of the sets of fixed points. These groups identify our cyclic homology groups with the ``orbifold cohomology'' of the underlying (algebraic) orbifold. The proof is based on a careful study of localization at fixed points and of the resulting Koszul complexes. We provide examples of Azumaya algebras for which this identification is, however, no longer valid. As an example, we discuss some affine Weyl groups.

Domaines: Mathématiques [math]; K-théorie et homologie [math.KT]; Géométrie algébrique [math.AG]

Brodzki Jacek, Dave Shantanu, Victor Nistor. The periodic cyclic homology of crossed products of finite type algebras. 2015. ⟨hal-01285204⟩