Classification of differentials and Cartan calculus on bicrossproducts

Abstract

We provide the Cartan calculus for bicovariant differential forms on bicrossproduct quantum groups $k(M)\lrbicross kG$ associated to finite group factorizations $X=GM$ and a field $k$. The irreducible calculi are associated to certain conjugacy classes in $X$ and representations of isotropy groups. We find the full exterior algebras and show that they are inner by a bi-invariant 1-form $\theta$ which is a generator in the noncommutative de Rham cohomology $H^1$. The special cases where one subgroup is normal are analysed. As an application, we study the noncommutative cohomology on the quantum codouble $D^*(S_3)\isom k(S_3)\lrbicross k\Z_6$ and the quantum double $D(S_3)=k(S_3)\lcross kS_3$, finding respectively a natural calculus and a unique calculus with $H^0=k.1$.

Minor revision: deleted six pages (mainly some examples) at request of referee. Now 30 pages latex, no figs