Twisted group algebras II

Wendel showed that norm non-increasing isomorphisms between the group algebras of locally compact groups could be expressed in terms of group characters and topological isomorphisms. His results are extended to twisted group algebras. In particular, by applying a generalisation ofWendel's main result to twisted group algebras over the same group, it is shown that the number of such algebras is equal to the number of orbits in a 2-cohomology group overG under the action of the automorphism group ofG. An application to the twisted group algebra defined byWeyl's form of the canonical commutation relations is considered.