//taken from Nowak, M. & R. May (1992) The Spatial Dilemmas of Evolution. International Journal of Bifurcation and Chaos, Vol. 3, No. 1 (1993) 35-78
1 //agent plays 1st strategy, opponent plays 1st strategy
1.85 //agent plays 2nd strategy, opponent plays 1st strategy
0 //agent plays 1st strategy, opponent plays 2nd strategy
0 //agent plays 2nd strategy, opponent plays 2nd strategy