What if you defect against Grim Trigger If you defect and the other guy is playing Grim Trigger, you will get a payoff of T>R the first time that you defect.
{"Image DocumentName": "When is there a symmetric SPNE where all play Grim Trigger?", "Image ImageDescription": "Suppose that the other player is playing Grim Trigger. If you play Grim Trigger as well, then you will cooperate as long as the game continues and and you will receive a payoff of R. Your expected payoff from playing Grim Trigger if the other guy is playing Grim Trigger is therefore. R(1+d +d2 + d3 + d4 + \u2026.+ )=R/(1-d)", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}