Complex sentence: In this symmetric situation, each side perceives itself as preferring to cooperate, if only the other side would, but each is forced by the strategy into repeatedly punishing an opponent who continues to attack despite being punished in every game cycle.
Split into simpler sentences: In this symmetric situation, each side perceives itself as preferring to cooperate, if only the other side would. But each is forced by the strategy into repeatedly punishing an opponent who continues to attack despite being punished in every game cycle.