This paper provides an overview of the various shapes the bestreply multifunctions can take in 2x2x2 trimatrix games. It is shown that, unlike in 2x2 bimatrix games, the best replies to the opponents pure strategies do not completely determine the structure of the Nash equilibrium set

Proper equilibrium plays a prominent role in the literature on non-cooperative games. The underlying thought experiment is, however, unsatisfying, as it gives no justification for its fundamental idea that severe mistakes are made with a significantly smaller probability than innocuous ones. In...