so i've moved on from marriage into imprisonment (can argue that's not changing anything at all, but whatever). i think this game theory should be named prisoners' dilemma, with the apostrophe moved over, since there are two prisoners. unless only one thinks. but both have a dilemma. prisoners' dilemmas? huh. anyway, two suspects are caught. each one is told they can sell out the other guy and they can go free and the other guy will get 10 years. if they both sell each other out, they both get 5 years. if both don't say anything, they just get 6 months. so the obvious answer is to sell the other guy out.
but being in jail once isn't fun enough, so they made an iterated prisoner's dilemma, which means this game is played n times (n being some number. i guess it should be a positive integer). according to john nash, the nash equilibrium is... sell the other guy out! the game eventually has to end (unless n is positive infinite. would it still be an integer?) and the prisoners know this. a prisoner would have to sell out on the other guy on the last turn, because there's no more chances to be punished by the other guy. since they are all going to sell each other out on the last turn, they should sell each other out the turn before. and the turn before. and the turn before. all the way to the beginning. (kind of reminds me of unexpected hanging paradox, which is a king tells some guy they are going to be hanged unexpectedly on some day this week. guy believes he won't die because if he's not killed by thursday, he'll know he will die on friday. which means he can't die on thursday, or he'll know by wednesday, etc. in the end, he's still hanged unexpectedly [because he came to the conclusion that he isn't].)
then there's some guy that made some "superrationality" approach to the iterated dilemma. a superrational prisoner will know when he's against another superrational prisoner and they'll act the same, because they can think of what is in each others' minds or something. so in this way, they will agree to be quiet sometimes. too bad we can't read other people's minds. and a superrational prisoner will know the other person is thinking of cooperating and then cheat him and win. and the other prisoner might think this and try to cheat back. and then in the end, they both are selling each other out again. maybe. i don't quite understand super things.
the some brilliant anatol rapoport guy wrote (well, typed) four lines of BASIC code and apparently it is the best results for some contest. and he won. basically his thing, called "tit for tat," is cooperate and then copy what the other person does the previous round. so there's lots of cooperation. and that is good. but the prisoner must have four traits: nice, retaliating, forgiving, and non-envious. nice being optimistic and cooperative. retaliating if the other person starts to retaliate. forgiving, which is to cooperate again if the person doesn't retaliate against the retaliation (so it doesn't cycle). non-envious is not trying to beat the other guy. some problems with this one is that sometimes it might go into an endless spiral of selling each other out. oh well, too bad. and too bad most people probably don't have all four traits. it's interesting though because it shows that the best strategy is to cooperate. this idea is kind of modeled after reciprocal altruism in biology (or did the idea of reciprocal altruism come after?). well, if this is the best strategy, should be applied to more of life, but i guess this is a long-run thing and in the long run we're all dead. so since we know there is an end, we should cheat at the very end. and this propagates forward, like nash equilibrium. too bad we must always win. i will win. short run is the best. leads to doom, but it's okay. like global warming, no one wants to lose their technological process by stopping.