Axelrod tournament — round-robin competition between strategies
Tournament scores
Head-to-head matrix (score per round)
200
0.00
5
1
Ready — click Run Tournament
Axelrod (1980) ran tournaments of the iterated Prisoner's Dilemma. Payoffs: T (temptation to defect) > R (reward for mutual cooperation) > P (punishment) > S (sucker's payoff). Tit-for-Tat (TFT) won both tournaments: cooperate first, then copy the opponent's last move. Key insight: cooperation emerges when games are repeated (shadow of the future). With noise, Pavlov (Win-Stay/Lose-Shift) outperforms TFT by recovering from accidental defections. AllD dominates only when facing always-cooperators.