So we turned into Barney Kiernan’s and there sure enough was the citizen up in the corner having a great confab with himself
Theorists have studied Prisoner’s Dilemma for decades, using it as a model for the emergence of co-operation in nature. This work has had a profound impact on disciplines such as economics, evolutionary biology and, of course, game theory itself. The new result will have impact in all these areas and more. […]
The game is this: imagine Alice and Bob have committed a crime and are arrested. The police offer each one a deal–snitch and you go free while your friend does 6 months in jail. If both Alice and Bob snitch, they both get 3 months in jail. If they both remain silent, they both get one month in jail for a lesser offence.
What should Alice and Bob do?
If they co-operate, they both spend only one month in jail. Nevertheless, in a single game, the best strategy is to snitch because it guarantees that you don’t get the maximum jail term.
However, the game gets more interesting when played in repeated rounds because players who have been betrayed in one round have the chance to get their own back in the next iteration.
Until now, everyone thought the best strategy in iterative prisoner’s dilemma was to copy your opponents behaviour in the previous round. This tit-for-tat approach guarantees that you both spend the same time in jail.
That conclusion was based on decades of computer simulations and a certain blind faith in the symmetry of the solution.
So the news that there are other strategies that allow one player to not only beat the other but to determine their time in jail is nothing short of revolutionary.