Equivariant $\KK$-theory for generalised actions and Thom isomorphism in groupoid twisted $\K$-theory

Abstract

We develop equivariant KK-theory for locally compact groupoid actions by Morita equivalences on real and complex graded C*-algebras. Functoriality with respect to generalised morphisms and Bott periodicity are discussed. We introduce Stiefel-Whitney classes for real or complex equivariant vector bundles over locally compact groupoids to establish the Thom isomorphism theorem in twisted groupoid K-theory.

arXiv comment21 pages, abstract changed, introductory exposition improved, minor corrections. Accepted for publication in J. K-theory