There are two versions of this paper. In the abridged version (47 pages) the proofs of the lemmata, some material on symmetry of equilibrium, and the proof of existence of equilibrium have been removed. The abridged version has been accepted at the Journal of Economic Theory. The unabridged version (78 pages) is a revised version of University of Arizona Working Paper 99-05.

This material is based upon work supported by the National Science Foundation under Grant No. 9810481. Any opinions, findings and conclusions or recomendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).