Complete conditional type structures

Abstract

Hierarchies of conditional beliefs (Battigalli and Siniscalchi, 1999) play a central role for the epistemic analysis of solution concepts in sequential games. They are modelled by type structures, which allow the analyst to represent the players' hierarchies without specifying an infinite sequence of conditional beliefs. Here, we study type structures that satisfy a “richness” property, called completeness. Friedenberg (2010) shows that, under specific conditions, a complete type structure with ordinary beliefs represents all hierarchies. This paper shows that Friedenberg's result can be extended to type structures with conditional beliefs. As an ancillary result of independent interest, we provide a construction of the “canonical” space of hierarchies of conditional beliefs which generalizes the one in Battigalli and Siniscalchi (1999).