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. 2013 May 22;8(5):e63761. doi: 10.1371/journal.pone.0063761

Figure 2. The snowdrift game with varying combinations of r and w, under low and high costs.

Figure 2

Panel A shows the snowdrift game under low cost (where b/2– c >0; values used were b = 2.4, c = 1). At low r and w, a mixed strategy of TFT and D is the ESS. At high r and w, All-TFT becomes the global ESS, and once r is sufficiently large, All-C can be an ESS. Panel B shows that higher values of r and w are required to promote cooperation when costs of cooperating are higher (where b/2– c <0, values used were b = 2.4, c = 1.5). Because the D and TFT ESS isolegs cross, there are four regions of outcomes: 1) All-D is a global ESS, 2) All-D or All-TFT is local ESS (alternate stable states), 3) a mixture of TFT and D are a global ESS, and 4) All-TFT is the global ESS. All-C can be an ESS when r>c/b.