Schur’s double centralizer theorem for triangular Hopf algebras

Burnside's Theorem for Hopf Algebras

A classical theorem of Burnside asserts that if X is a faithful complex character for the finite group G, then every irreducible character of G is a constituent of some power Xn of X . Fifty years after this appeared, Steinberg generalized it to a result on semigroup algebras K[G] with K an arbitrary field and with G a semigroup, finite or infinite. Five years later, Rieffel showed that the the...

Braided Hopf algebras of triangular type

A Frobenius-Schur theorem for Hopf algebras

In this note we prove a generalization of the Frobenius-Schur theorem for finite groups for the case of semisimple Hopf algebra over an algebraically closed field of characteristic 0. A similar result holds in characteristic p > 2 if the Hopf algebra is also cosemisimple. In fact we show a more general version for any finite-dimensional semisimple algebra with an involution; this more general r...

Serre Theorem for Involutory Hopf Algebras

Let H be an involutory Hopf algebra over a field of characteristic zero, M and N two finite dimensional left H-modules such that M ⊗ N is a semisimple H-module. Then M and N are semisimple H-modules. This is a generalization of a theorem proved by J.-P. Serre for group algebras. A version of the theorem above for monoidal categories is also given.

4 Triangular braidings and pointed Hopf algebras ⋆

We consider an interesting class of braidings defined in [1] by a combinatorial property. We show that it consists exactly of those braidings that come from certain Yetter-Drinfeld module structures over pointed Hopf algebras with abelian coradical. As a tool we define a reduced version of the FRT construction. For braidings induced by Uq(g)-modules the reduced FRT construction is calculated ex...