Compact open sets in dual spaces and projections in group algebras of [FC]− groups

摘要

The structure of a compact open set in the dual of an [FC]− group G, a locally compact group with relatively compact conjugacy classes, is given in terms of certain subsets which arise somewhat naturally. The support in the dual of a projection in L 1(G) is a compact open set. Therefore, knowledge of the structure of such sets helps in identifying and constructing projections. We describe explicitly the compact open sets and construct projections for some illustrative examples.