An Exponentially Converging Particle Method for the Mixed Nash Equilibrium of Continuous Games

Fuente: arXiv
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Autores principales: Wang, Guillaume, Chizat, Lénaïc
Formato: Preprint
Publicado: 2022
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author Wang, Guillaume
Chizat, Lénaïc
author_facet Wang, Guillaume
Chizat, Lénaïc
contents We consider the problem of computing mixed Nash equilibria of two-player zero-sum games with continuous sets of pure strategies and with first-order access to the payoff function. This problem arises for example in game-theory-inspired machine learning applications, such as distributionally-robust learning. In those applications, the strategy sets are high-dimensional and thus methods based on discretisation cannot tractably return high-accuracy solutions. In this paper, we introduce and analyze a particle-based method that enjoys guaranteed local convergence for this problem. This method consists in parametrizing the mixed strategies as atomic measures and applying proximal point updates to both the atoms' weights and positions. It can be interpreted as a time-implicit discretization of the "interacting" Wasserstein-Fisher-Rao gradient flow. We prove that, under non-degeneracy assumptions, this method converges at an exponential rate to the exact mixed Nash equilibrium from any initialization satisfying a natural notion of closeness to optimality. We illustrate our results with numerical experiments and discuss applications to max-margin and distributionally-robust classification using two-layer neural networks, where our method has a natural interpretation as a simultaneous training of the network's weights and of the adversarial distribution.
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id arxiv_https___arxiv_org_abs_2211_01280
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle An Exponentially Converging Particle Method for the Mixed Nash Equilibrium of Continuous Games
Wang, Guillaume
Chizat, Lénaïc
Optimization and Control
Computer Science and Game Theory
Machine Learning
We consider the problem of computing mixed Nash equilibria of two-player zero-sum games with continuous sets of pure strategies and with first-order access to the payoff function. This problem arises for example in game-theory-inspired machine learning applications, such as distributionally-robust learning. In those applications, the strategy sets are high-dimensional and thus methods based on discretisation cannot tractably return high-accuracy solutions. In this paper, we introduce and analyze a particle-based method that enjoys guaranteed local convergence for this problem. This method consists in parametrizing the mixed strategies as atomic measures and applying proximal point updates to both the atoms' weights and positions. It can be interpreted as a time-implicit discretization of the "interacting" Wasserstein-Fisher-Rao gradient flow. We prove that, under non-degeneracy assumptions, this method converges at an exponential rate to the exact mixed Nash equilibrium from any initialization satisfying a natural notion of closeness to optimality. We illustrate our results with numerical experiments and discuss applications to max-margin and distributionally-robust classification using two-layer neural networks, where our method has a natural interpretation as a simultaneous training of the network's weights and of the adversarial distribution.
title An Exponentially Converging Particle Method for the Mixed Nash Equilibrium of Continuous Games
topic Optimization and Control
Computer Science and Game Theory
Machine Learning
url https://arxiv.org/abs/2211.01280