1. Explain why the rules of Axelrod's tournament favored tit-for-tat. What strategy would best tit-for-tat head to head? What does this suggest about the reasonableness of the SPNE?
2. During the Great War of 1914-18, German and British soldiers engaged in trench warfare where units faced each other across the trenches for long periods of time. Instead of following official orders to shoot each other as often as possible, some units would establish a "live and let live" policy with the other side where they could walk above ground in safety and even fraternize with the enemy. Axelrod argues in his case study that these instances represent cooperative equilibria to repeated Prisoners' Dilemma games.