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AFAIK the strategy was slightly different: You start collaborative, and then simply repeat the other person's last action. This means that, if they screw you, you keep screwing them until they turn collaborative, at which point you collaborate in the next iteration.

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Yup. In real situations, one element is that sometimes things are misunderstood, and in particular sometimes collaborating is mistaken for defecting, so if all sides are playing pure tit-for-tat, then one can end up in a defect-defect loop forever (or, I guess, until the opposite misinterpretation occurs). Therefore, an element of forgiveness (some percent chance that you'll respond to a defect with a cooperate) can be helpful.

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