Algorithms and Complexity for Computing Nash Equilibria in Adversarial Team Games

Fuente: arXiv
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Auteurs principaux: Anagnostides, Ioannis, Kalogiannis, Fivos, Panageas, Ioannis, Vlatakis-Gkaragkounis, Emmanouil-Vasileios, McAleer, Stephen
Format: Preprint
Publié: 2023
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author Anagnostides, Ioannis
Kalogiannis, Fivos
Panageas, Ioannis
Vlatakis-Gkaragkounis, Emmanouil-Vasileios
McAleer, Stephen
author_facet Anagnostides, Ioannis
Kalogiannis, Fivos
Panageas, Ioannis
Vlatakis-Gkaragkounis, Emmanouil-Vasileios
McAleer, Stephen
contents Adversarial team games model multiplayer strategic interactions in which a team of identically-interested players is competing against an adversarial player in a zero-sum game. Such games capture many well-studied settings in game theory, such as congestion games, but go well-beyond to environments wherein the cooperation of one team -- in the absence of explicit communication -- is obstructed by competing entities; the latter setting remains poorly understood despite its numerous applications. Since the seminal work of Von Stengel and Koller (GEB `97), different solution concepts have received attention from an algorithmic standpoint. Yet, the complexity of the standard Nash equilibrium has remained open. In this paper, we settle this question by showing that computing a Nash equilibrium in adversarial team games belongs to the class continuous local search (CLS), thereby establishing CLS-completeness by virtue of the recent CLS-hardness result of Rubinstein and Babichenko (STOC `21) in potential games. To do so, we leverage linear programming duality to prove that any $ε$-approximate stationary strategy for the team can be extended in polynomial time to an $O(ε)$-approximate Nash equilibrium, where the $O(\cdot)$ notation suppresses polynomial factors in the description of the game. As a consequence, we show that the Moreau envelop of a suitable best response function acts as a potential under certain natural gradient-based dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2301_02129
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Algorithms and Complexity for Computing Nash Equilibria in Adversarial Team Games
Anagnostides, Ioannis
Kalogiannis, Fivos
Panageas, Ioannis
Vlatakis-Gkaragkounis, Emmanouil-Vasileios
McAleer, Stephen
Computer Science and Game Theory
Computational Complexity
Data Structures and Algorithms
Adversarial team games model multiplayer strategic interactions in which a team of identically-interested players is competing against an adversarial player in a zero-sum game. Such games capture many well-studied settings in game theory, such as congestion games, but go well-beyond to environments wherein the cooperation of one team -- in the absence of explicit communication -- is obstructed by competing entities; the latter setting remains poorly understood despite its numerous applications. Since the seminal work of Von Stengel and Koller (GEB `97), different solution concepts have received attention from an algorithmic standpoint. Yet, the complexity of the standard Nash equilibrium has remained open. In this paper, we settle this question by showing that computing a Nash equilibrium in adversarial team games belongs to the class continuous local search (CLS), thereby establishing CLS-completeness by virtue of the recent CLS-hardness result of Rubinstein and Babichenko (STOC `21) in potential games. To do so, we leverage linear programming duality to prove that any $ε$-approximate stationary strategy for the team can be extended in polynomial time to an $O(ε)$-approximate Nash equilibrium, where the $O(\cdot)$ notation suppresses polynomial factors in the description of the game. As a consequence, we show that the Moreau envelop of a suitable best response function acts as a potential under certain natural gradient-based dynamics.
title Algorithms and Complexity for Computing Nash Equilibria in Adversarial Team Games
topic Computer Science and Game Theory
Computational Complexity
Data Structures and Algorithms
url https://arxiv.org/abs/2301.02129