And my decision in round 99 is also part if Iterated Prisoners Dilemma. My decision in round 100 is no longer iterated PD, but normal PD with additional information about how my partner played a IPD.
Key feature of PD as opposed to IPD: In Prisoner's Dilemma, you will never, ever, interact with the other player again. If that's a possibility, then you are playing a game with many similarities but a different premise.
As you said, a key feature of PD is that you're not ever going to interact with the other player again, so while the last round may perhaps be interpreted as PD, the second-to-last round may not.
Of course you could just as well argue that a key feature of PD is also that you have never interacted with the other player before. That's my point of view, but in the end this is an academic question.
It doesn't matter: 100-round IPD only becomes 99-round IPD if you have 100% confidence that Clippy's decision in round 100 is not in any way causally related to your...
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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