  Credible equilibrium is a solution concept that imposes a stronger
credibility notion than subgame perfect equilibrium. A credible equilibrium is
a refinement of subgame perfect equilibrium such that if a threat in a subgame
g is "credible," then it must also be credible in every subgame g' that is
"equivalent" to g. I show that (i) a credible equilibrium exists in multi-stage
games, and (ii) if every stage game has a unique Nash equilibrium, then the
credible equilibrium is unique even in infinite horizon multi-stage games.
Moreover, in perfect information games, credible equilibrium is equivalent to
subgame perfect equilibrium.
