Computing Game Symmetries and Equilibria That Respect Them

Fuente: arXiv
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Autores principales: Tewolde, Emanuel, Zhang, Brian Hu, Oesterheld, Caspar, Sandholm, Tuomas, Conitzer, Vincent
Formato: Preprint
Publicado: 2025
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author Tewolde, Emanuel
Zhang, Brian Hu
Oesterheld, Caspar
Sandholm, Tuomas
Conitzer, Vincent
author_facet Tewolde, Emanuel
Zhang, Brian Hu
Oesterheld, Caspar
Sandholm, Tuomas
Conitzer, Vincent
contents Strategic interactions can be represented more concisely, and analyzed and solved more efficiently, if we are aware of the symmetries within the multiagent system. Symmetries also have conceptual implications, for example for equilibrium selection. We study the computational complexity of identifying and using symmetries. Using the classical framework of normal-form games, we consider game symmetries that can be across some or all players and/or actions. We find a strong connection between game symmetries and graph automorphisms, yielding graph automorphism and graph isomorphism completeness results for characterizing the symmetries present in a game. On the other hand, we also show that the problem becomes polynomial-time solvable when we restrict the consideration of actions in one of two ways. Next, we investigate when exactly game symmetries can be successfully leveraged for Nash equilibrium computation. We show that finding a Nash equilibrium that respects a given set of symmetries is PPAD- and CLS-complete in general-sum and team games respectively -- that is, exactly as hard as Brouwer fixed point and gradient descent problems. Finally, we present polynomial-time methods for the special cases where we are aware of a vast number of symmetries, or where the game is two-player zero-sum and we do not even know the symmetries.
format Preprint
id arxiv_https___arxiv_org_abs_2501_08905
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Computing Game Symmetries and Equilibria That Respect Them
Tewolde, Emanuel
Zhang, Brian Hu
Oesterheld, Caspar
Sandholm, Tuomas
Conitzer, Vincent
Computer Science and Game Theory
Artificial Intelligence
Computational Complexity
Multiagent Systems
91A05, 91A06, 91A10, 91A26, 91A35, 91A68, 68Q17, 68Q25, 68T01
I.2; J.4; F.2
Strategic interactions can be represented more concisely, and analyzed and solved more efficiently, if we are aware of the symmetries within the multiagent system. Symmetries also have conceptual implications, for example for equilibrium selection. We study the computational complexity of identifying and using symmetries. Using the classical framework of normal-form games, we consider game symmetries that can be across some or all players and/or actions. We find a strong connection between game symmetries and graph automorphisms, yielding graph automorphism and graph isomorphism completeness results for characterizing the symmetries present in a game. On the other hand, we also show that the problem becomes polynomial-time solvable when we restrict the consideration of actions in one of two ways. Next, we investigate when exactly game symmetries can be successfully leveraged for Nash equilibrium computation. We show that finding a Nash equilibrium that respects a given set of symmetries is PPAD- and CLS-complete in general-sum and team games respectively -- that is, exactly as hard as Brouwer fixed point and gradient descent problems. Finally, we present polynomial-time methods for the special cases where we are aware of a vast number of symmetries, or where the game is two-player zero-sum and we do not even know the symmetries.
title Computing Game Symmetries and Equilibria That Respect Them
topic Computer Science and Game Theory
Artificial Intelligence
Computational Complexity
Multiagent Systems
91A05, 91A06, 91A10, 91A26, 91A35, 91A68, 68Q17, 68Q25, 68T01
I.2; J.4; F.2
url https://arxiv.org/abs/2501.08905