Page "Subgame" Paragraph 8

In a Nash equilibrium, there is some sense in which the outcome is optimal-every player is playing a best response to the other players.

However, in some dynamic games this can yield implausible equilibria.

Consider a two-player game in which player 1 has a strategy S to which player 2 can play B as a best response.

Suppose also that S is a best response to B.

Hence,