Weight theory for C*-algebraic quantum groups

Abstract

In this paper, we collect some technical results about weights on C*-algebras which are useful in de theory of locally compact quantum groups in the C*-algebra framework. We discuss the extension of a lower semi-continuous weight to a normal weight following S. Baaj, look into slice weights and their KSGNS-constructions and investigate the tensor product of weights together with a partial GNS-construction for such a tensor product. This paper accompanies our paper 'Locally compact quantum groups' in which we propose a relatively simple definition of a locally compact quantum group in the C*-algebra framework.