Prisoner's Dilemma

Prisoner's Dilemma is a good know problem in a field of game theory. Essence of Prisoner's Dilemma lie on the decisions of two prisoners arrested for the same crime, for example robbing some bank. Prisoners are separated in two rooms and each other isn't aware about the decision of the second one.

There are three possible situations, which can happen:
1) Prisoners betrays each other, and each of them stay in jail for 5 years.
2) Both prisoners stays silent, and each of them stay in jail for 2 year.
3) First prisoner betrays the second one, but the second one stays silent. The first prisoner will be free, but the second one stays in jail for 10 years.

The matrix below reflects this situation:

	Prisoner 2 Stays Silent	Prisoner 2 Betrays
Prisoner 1 Stays Silent	2 years for each	10 years for Prisioner 1 0 years for Prisioner 2
Prisoner 1 Betrays	0 years for Prisioner 1 10 years for Prisioner 2	5 yearch for each

If the first prisoner betrays the second one, and the second one stays silent, the first prisoner will be free, but the second prisoner will be arrested for 10 years. This is the best situation for the first prisoner, but the worst for the second prisoner.

But the second prisoner also wants to spend the shortest time possible in the jail, so he is thinking if the first prisoner betrays him, or stay silent. He knows that there is a possibility that the first prisoner betrays him and he knows that in this case it is better to betray the first prisoner also.

You can try Prisoner's Dilemma online game here

Sources:
http://plato.stanford.edu/entries/prisoner-dilemma/
http://en.wikipedia.org/wiki/Prisoner%27s_dilemma