Simple coalitional strategy profiles in repeated games

•Simple coalitional strategy profiles to avoid group deviations are introduced.•Only one-shot deviations need to be checked to avoid coalitional deviations.•The concept of Quasi Strong Perfect Equilibrium (QSPE) is analyzed.•In the Cournot supergame the symmetric monopoly outcome can be sustained by a QSPE.

In this paper we introduce simple coalitional strategy profiles to avoid group deviations in repeated games. In the repeated Cournot supergame we prove that it is possible to sustain the symmetric monopoly outcome by means of a variety of strategies which satisfy the requirement that no coalition (other than the grand one) will deviate in any subgame.