C
D
C
1,1
0,b
D
b,0
0,0
Nowak & May, Nature 1992
Payoff: C vs C → (1,1), C vs D → (0,b), D vs D → (0,0). Each cell plays all 8 neighbors, scores payoffs, imitates best-scoring neighbor (including self).
Spatial structure allows cooperators to form clusters — mutual protection against defection. Cooperation survives for b<~1.8.
Payoff: C vs C → (1,1), C vs D → (0,b), D vs D → (0,0). Each cell plays all 8 neighbors, scores payoffs, imitates best-scoring neighbor (including self).
Spatial structure allows cooperators to form clusters — mutual protection against defection. Cooperation survives for b<~1.8.