The point that I didn't see made yet is that it's only Iterated Prisoner's Dilemma for the first N-1 times. After that it's simply singe PD.
Of course, N-1 becomes the new N, so it's just a combination of providing a signal to the other player about what kind of decisions you make while also interpreting the signals they are sending about the kind of decisions they make. Dual-cooperation is the best likely outcome over a number of iterations, so the goal of the signalling should be to convince other player to cooperate. "Cooperate now and I will cooperate next round, defect now and I will defect next round" is a perfectly valid signal to try to send.
The point that I didn't see made yet is that it's only Iterated Prisoner's Dilemma for the first N-1 times. After that it's simply singe PD.
It is not correct to say that the last round is simple PD, because each player has additional information at that point. Consequentially, while the decision for round N is the same as in PD, N-1 does not actually become the new N.
Today's post, The Truly Iterated Prisoner's Dilemma was originally published on 04 September 2008. A summary (taken from the LW wiki):
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