In this note we present an example of a repeated partnership game with imperfect monitoring in which all supergame equilibria with positive discount rates are bounded away from full efficiency uniformly in the discount rate, provided the latter is strictly positive. On the other hand, if the players do not discount the future, then every efficient one-period payoff vector that dominates the one-period equilibrium payoff vector can be attained by an equilibrium of the repeated game. Thus the correspondence that maps the players' discount rate into the corresponding set of repeated-game equilibrium payoff vectors is discontinuous at the point at which the discount rate is zero.

Partha Dasgupta, Peter Hammond, Eric Maskin; The Implementation of Social Choice Rules: Some General Results on Incentive Compatibility, The Review of Econ

This paper studies the set of equilibrium payoffs in repeated games with long- and short-run players and little discounting. Because the short-run players are unconcerned about the future, each equilibrium outcome is constrained to lie on their static reaction (best-response) curves. The natural extension of the folk theorem to games of this sort would simply include this constraint in the definitions of the feasible payoffs and minmax values. In fact, this extension does obtain under the assumption that each player's choice of a mixed strategy for the stage game is publicly observable but, in contrast to standard repeated games, the set of equilibrium payoffs is different if players can observe only their opponents' realized actions.