The Tit-for-Tat Solution

The TFT strategy consisted of the following:

  • Cooperate on the first move.
  • Echo your opponent’s move each time thereafter.

So if the opponent cooperates on any given move, TFT cooperates on the next one. If the opponent defects, so does TFT, but if the opponent then changes back to cooperating, TFT immediately returns to cooperating as well. The program never defects first, retaliates immediately, and also forgives immediately.

After the tournament, Axelrod released all of the programs to the participants and stated that he planned to hold another tournament soon. TFT would be included in the new tournament, and additional programs were also going to be solicited from economists, mathematicians, social scientists, and more. ...

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