BLACK-HOLES AND WORMHOLES IN 2+1 DIMENSIONS

A large variety of spacetimes-including the BTZ black holes-can be obt ained by identifying points in (2 + 1)-dimensional anti-de Sitter spac e by means of a discrete group of isometries. We consider all such spa cetimes that can be obtained under a restriction to time-symmetric ini tial data and one asymptotic region only. The resulting spacetimes are non-eternal black holes with collapsing wormhole topologies. Our appr oach is geometrical, and we discuss in detail the allowed topologies, the shape of the event horizons, topological censorship and trapped cu rves.