Matsushima, Hitoshi

We investigate an infinitely repeated prisoners' dilemma with imperfect monitoring and projects the possibility that the interlinkage of the players' distinct activities enhances implicit collusion. We show a necessary and sufficient condition for the existence of generous tit-for-tat Nash equilibrium. Such an equilibrium, if it exists, is unique. This equilibrium achieves approximate efficiency when monitoring is almost perfect, where the discount factors are fixed.