From: Environmental adversity and uncertainty favour cooperation
X ¯ MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGacaGaaiaabeqaaeqabiWaaaGcbaWaa0aaaeaacqWGybawaaaaaa@2D1D@
Cooperate
Compete
f ( R 1 ) + Δ 2 , f ( R 2 ) + Δ 2 MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGacaGaaiaabeqaaeqabiWaaaGcbaGaemOzay2aaeWaaeaacqWGsbGudaWgaaWcbaGaeGymaedabeaaaOGaayjkaiaawMcaaiabgUcaRKqbaoaalaaabaGaeuiLdqeabaGaeGOmaidaaOGaeiilaWIaemOzay2aaeWaaeaacqWGsbGudaWgaaWcbaGaeGOmaidabeaaaOGaayjkaiaawMcaaiabgUcaRKqbaoaalaaabaGaeuiLdqeabaGaeGOmaidaaaaa@3ED1@
α · f(R1), f(R2) + Δ
f(R1) + Δ, α · f(R2)
f(R1), f(R2)