Cycle avoiding trajectories, strategic agendas, and the duality of memory and foresight: An informal exposition

Abstract

This paper considers the notion of cycle avoiding trajectories in majority voting tournaments and shows that they underlie and guide several apparently disparate voting processes. The set of alternatives that are maximal with respect to such trajectories constitutes a new solution set of considerable significance. It may be dubbed the Banks set, in recognition of the important paper by Banks (1985) that first made use of this set. The purpose of this paper is to informally demonstrate that the Banks set is a solution set of broad relevance for understanding group decision making in both cooperative and non-cooperative settings and under both sincere and sophisticated voting. In addition, we show how sincere and sophisticated voting processes can be viewed as mirror images of one another — embodying respectively, “dmemory” and “foresight.” We also show how to develop the idea of a “sophisticated agenda,” one in which the choice of what alternatives to propose is itself a matter of strategic calculation.