In: Economics
Consider the following two-player game:
L | C | R | |
T | 2,2 | 0,2 | 0,1 |
M | 2,0 | 1,1 | 0,2 |
B | 1,0 | 2,0 | 0,0 |
(a) Find all pure strategy Nash equilibria of this game.
(b) Consider the following procedure of iterated elimination of weakly dominated actions : all weakly dominated actions of each player are eliminated at each stage. What are the action profiles that survive this procedure in the above game?
I have no problem with solving (a) but (b) is so difficult. This is a question From Osborne's An introduction to game theory. Excercise 391.1. Even though there's a solution available at Chegg, I can't follow the explanation.
b) Since it there are weakly dominated strategies, the equilibrium depends on the order of elimination of strategies. Let us consider T and M for player 1. We see that if Player 2 plays L, Player 1 has the same payoff in T and M. If player 2 plays C, Player 1 has better payout with M and if Player 2 plays R, player A has same payoff in T and M. So M weakly dominates T. So we can eliminate T. The resulting table will be
L | C | R | |
M | 2,0 | 1,1 | 0,1 |
B | 1,0 | 2,0 | 0,0 |
Now for Player 2, let us consider L and C.
When player 1 plays M, Player 2 has better payoff with C and when player 1 plays B, player 2 has same payoff with L and C.
So C weakly dominates L.
Thus we can eliminate L.
The resulting table is
C | R | |
M | 1,1 | 0,1 |
B | 2,0 | 0,0 |
Again let us move to player 1. When player 2 plays C, Player 1 has a better payoff with B. When player 2 plays R, player 1 has same payoff with M and B. So B weakly dominates over M.
So the resultant table is
C | R | |
B | 2,0 | 0,0 |
Here we see that player 2 has the same payoff in both cases. However, since our assumption is all individuals are rational, player 2 will choose C so that Player 1 has a higher payoff.
So the effective equilibrium will be when Player 2 chooses C and player 1 chooses B.
However, this can change if our order of iterated elimination of weakly dominated strategy changes. So this is one of many solutions
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