Show that, as long as k is large enough, the alternating strategy (a) defined below is a better reply to strategy τ than τ is to itself. Is strategy a a Nash equilibrium in this case? If not, what is?...

Show that, as long as k is large enough, the alternating strategy (a) defined below is a better reply to strategy τ than τ is to itself. Is strategy a a Nash equilibrium in this case? If not, what is?

Problems 5.3, 5.4 and 5.5 below refer to the Prisoner’s Dilemma in which you play against an opponent with the following pay-offs: