Evolutionary Prisoner's Dilemma Tournaments
Evolutionary Prisoner's Dilemma Tournaments
The prisoner's dilemma is a two-player game in which each player (prisoner) can either "cooperate" (stay silent) or "defect" (betray the other prisoner). If both players cooperate, they each get a reward ; if both defect, they get a punishment payoff ; if one player defects and the other cooperates, the defecting player gets a temptation payoff , while the cooperating player receives a sucker payoff . In the standard form of the game,
R
P
T
S
R=3
P=1
T=5
S=0
This Demonstration illustrates an evolutionary tournament based on the prisoner's dilemma that proceeds as follows: In the initial generation there are five players, each playing a particular strategy. These players then conduct a tournament in which each pair of players plays a large number of rounds of the prisoner's dilemma game using their respective strategies. The second generation consists of the same set of player types and player strategies, but redistributed according to the payoffs in this tournament. For example, if player 1's payoff was twice that of player 2, the second generation will include twice as many copies of player 1 (with each playing the strategy of player 1) as of player 2. Continuing this process over many generations, we find that some strategies tend to become dominant, while others die out. This Demonstration shows the evolution of player populations over 20 generations.