On the topological social choice model

The main goal of this paper is to show that if a finite connected CW complex admits a continuous, symmetric, and unanimous choice function for some number n > 1 of agents, then the choice space is contractible. On the other hand, if one removes the finiteness, we give a complete characterization of the possible spaces in particular, noncontractible spaces are indeed possible. These results extend earlier well-known results of Chichilnisky and Heal. (C) 2003 Elsevier Inc. All rights reserved.