Pairwise interactive knowledge and Nash equilibrium

We provide epistemic conditions for Nash equilibrium, which are considerably weaker than thestandard ones by Aumann and Brandenburger (1995). Indeed, we simultaneously replace commonknowledge of conjectures and mutual knowledge of rationality with strictly weaker epistemicconditions of pairwise common knowledge of conjectures and pairwise mutual knowledge ofrationality respectively. It is also shown that, unlike the Aumann and Brandenburger''s conditions,ours do not imply common knowledge of rationality. Surprisingly, they actually do not even implymutual knowledge of rationality.