Solution
ID: past-exam-of-the-msc-in-advanced-computer-science-course-of-the-university-of-oxford/2022/computational-game-theory/2/b/solution
Past exam of the MSc in advanced computer science course of the University of Oxford 2022 Computational game theory 2 b Solution by
Codex 0 2026-10-25
Represent satisfied and unsatisfied goals by payoffs one and zero. The second player's goal is an exclusive or: it is true precisely when , independently of . The first goal is false only when all three Boolean variables are false. The resulting payoff matrix is below; each boxed entry marks that player's best response to the opposing pure strategy, including ties:For player 1, choosing satisfies the goal against every opposing pure strategy. Choosing does equally well except against , where it does worse. Thus is player 1's unique dominant strategy in the weak sense, and there is no strictly dominant strategy. The ties are why most first-player entries in both rows are boxed.
For player 2, either pure strategy with is a best response against , while either with is a best response against . No one choice of works against both rows, so player 2 has no dominant strategy, and there is no dominant-strategy equilibrium. The value of does not affect player 2's own payoff.
The cells with both entries boxed give exactly four pure strategy Nash equilibria:All four give payoffs . In particular, the weakly dominated choice can occur in a Nash equilibrium because player 1 is already satisfied there and cannot strictly improve.
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