  There are two well-known sufficient conditions for Nash equilibrium in
two-player games: mutual knowledge of rationality (MKR) and mutual knowledge of
conjectures. MKR assumes that the concept of rationality is mutually known. In
contrast, mutual knowledge of conjectures assumes that a given profile of
conjectures is mutually known, which has long been recognized as a strong
assumption. In this note, we introduce a notion of "mutual assumption of
rationality and correctness" (MARC), which conceptually aligns more closely
with the MKR assumption. We present two main results. Our first result
establishes that MARC holds in every two-person zero-sum game. In our second
theorem, we show that MARC does not in general hold in n-player games.
