Admissibility and assumption.

Brandenburger et al. (2008) defined the epistemic condition rationality and common assumption of rationality (RCAR) in lexicographic type structures. We define RCAR in the space of coherent lexicographic belief hierarchies and show that it is an epistemic condition for iterated admissibility. We also show that some coherent lexicographic belief hierarchies cannot be represented as types in lexicographic type structures. An advantage of this approach is that RCAR is possible in a canonical hierarchy space.