  We characterize common assumption of rationality of 2-person games within an
incomplete information framework. We use the lexicographic model with
incomplete information and show that a belief hierarchy expresses common
assumption of rationality within a complete information framework if and only
if there is a belief hierarchy within the corresponding incomplete information
framework that expresses common full belief in caution, rationality, every good
choice is supported, and prior belief in the original utility functions.
