STRONGLY CONSISTENT 2-PLAYER GAME FORMS

A two-player game form is Nash-consistent if and only if it is tight. Nash-consistency therefore depends only on the effectivity function as sociated with the game form. This fact is no longer true for strong co nsistency. We introduce the joint exact effectivity set which is a pro per refinement of the effectivity function and prove that a two-player game form is strongly consistent if and only if it is tight and joint ly exact. Joint exactness states that the new set coincides basically with the effectivity function.