We define and analyze "strategic topologies" on types, under which two types are close if their strategic behavior will be similar in all strategic situations. To oper- ationalize this idea, we adopt interim rationalizability as our solution concept, and define a metric topology on types in the...

This paper proposes the solution concept of interim rationalizability, and shows that all type spaces that have the same hierarchies of beliefs have the same set of interim rationalizable outcomes. This solution concept characterizes common knowledge of rationality in the universal type space.