The Complexity of Symmetric Bimatrix Games with Common Payoffs

Fuente: arXiv
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Autori principali: Ghosh, Abheek, Hollender, Alexandros
Natura: Preprint
Pubblicazione: 2024
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author Ghosh, Abheek
Hollender, Alexandros
author_facet Ghosh, Abheek
Hollender, Alexandros
contents We study symmetric bimatrix games that also have the common-payoff property, i.e., the two players receive the same payoff at any outcome of the game. Due to the symmetry property, these games are guaranteed to have symmetric Nash equilibria, where the two players play the same (mixed) strategy. While the problem of computing such symmetric equilibria in general symmetric bimatrix games is known to be intractable, namely PPAD-complete, this result does not extend to our setting. Indeed, due to the common-payoff property, the problem lies in the lower class CLS, ruling out PPAD-hardness. In this paper, we show that the problem remains intractable, namely it is CLS-complete. On the way to proving this result, as our main technical contribution, we show that computing a Karush-Kuhn-Tucker (KKT) point of a quadratic program remains CLS-hard, even when the feasible domain is a simplex.
format Preprint
id arxiv_https___arxiv_org_abs_2410_08031
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Complexity of Symmetric Bimatrix Games with Common Payoffs
Ghosh, Abheek
Hollender, Alexandros
Computer Science and Game Theory
Computational Complexity
We study symmetric bimatrix games that also have the common-payoff property, i.e., the two players receive the same payoff at any outcome of the game. Due to the symmetry property, these games are guaranteed to have symmetric Nash equilibria, where the two players play the same (mixed) strategy. While the problem of computing such symmetric equilibria in general symmetric bimatrix games is known to be intractable, namely PPAD-complete, this result does not extend to our setting. Indeed, due to the common-payoff property, the problem lies in the lower class CLS, ruling out PPAD-hardness. In this paper, we show that the problem remains intractable, namely it is CLS-complete. On the way to proving this result, as our main technical contribution, we show that computing a Karush-Kuhn-Tucker (KKT) point of a quadratic program remains CLS-hard, even when the feasible domain is a simplex.
title The Complexity of Symmetric Bimatrix Games with Common Payoffs
topic Computer Science and Game Theory
Computational Complexity
url https://arxiv.org/abs/2410.08031