Gravitational Collapse of Massless Scalar Field with Negative   Cosmological Constant in (2+1) Dimensions
  The 2+1-dimensional geodesic circularly symmetric solutions of Einstein-massless-scalar field equations with negative cosmological constant are found and their local and global properties are studied. It is found that one of them represents gravitational collapse where black holes are always formed. 
R. Chan, M. F. A. da Silva, Jaime F. Villas da Rocha