Settling the complexity of computing approximate two-player Nash equilibria
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Abstract (arXiv)
We prove that there exists a constant ε>0 such that, assuming the Exponential Time Hypothesis for PPAD, computing an ε-approximate Nash equilibrium in a two-player (nXn) game requires quasi-polynomial time, n^log1-o(1) n. This matches (up to the o(1) term) the algorithm of Lipton, Markakis, and Mehta [LMM03]. Our proof relies on a variety of techniques from the study of probabilistically checkable proofs (PCP); this is the first time that such ideas are used for a reduction between problems inside PPAD. En route, we also prove new hardness results for computing Nash equilibria in games with many players. In particular, we show that computing an ε-approximate Nash equilibrium in a game with n players requires 2Omega(n) oracle queries to the payoff tensors. This resolves an open problem posed by Hart and Nisan [HN13], Babichenko [Bab14], and Chen et al. [CCT15]. In fact, our results for n-player games are stronger: they hold with respect to the (ε,δ)-WeakNash relaxation recently introduced by Babichenko et al. [BPR16].
Key facts. Cited by 31 papers in the map (data through 7 Oct 2026). First posted on arXiv 14 Jun 2016.
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Citing papers per year: 2021: 3; 2022: 6; 2023: 8; 2024: 3; 2025: 7; 2026: 4.
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- 2023Hardness of Independent Learning and Sparse Equilibrium Computation in Markov Games22 Mar 2023
- 2023PAPAL: A Provable PArticle-based Primal-Dual ALgorithm for Mixed Nash Equilibrium2 Mar 2023
- 2023Breaking the Curse of Multiagency: Provably Efficient Decentralized Multi-Agent RL with Function Approximation13 Feb 2023
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- 2022Minimax-Optimal Multi-Agent RL in Markov Games With a Generative Model22 Aug 2022
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- 2022Provably Efficient Offline Multi-agent Reinforcement Learning via Strategy-wise Bonus1 Jun 2022
- 2022The Complexity of Markov Equilibrium in Stochastic Games8 Apr 2022
- 2021Near-Optimal No-Regret Learning for Correlated Equilibria in Multi-Player General-Sum Games11 Nov 2021
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- 2022Minimax-Optimal Multi-Agent RL in Markov Games With a Generative Modelcited by 15
- 2023On the Convergence of No-Regret Learning Dynamics in Time-Varying Gamescited by 14
- 2022Learning in Congestion Games with Bandit Feedbackcited by 10
- 2023Hardness of Independent Learning and Sparse Equilibrium Computation in Markov Gamescited by 9
- 2023Multi-Player Zero-Sum Markov Games with Networked Separable Interactionscited by 8
- 2022Efficiently Computing Nash Equilibria in Adversarial Team Markov Gamescited by 6
12 most cited of 29 All 29 (JSON)
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- 2026Min-Max Optimization Requires Exponentially Many Queries13 May 2026
- 2026Taming the Curses of Multiagency in Robust Markov Games with Large State Space through Linear Function Approximation4 May 2026
- 2025Proximal Regret and Proximal Correlated Equilibria: A New Tractable Solution Concept for Online Learning and Games3 Nov 2025
- 2025Discovering Expert-Level Nash Equilibrium Algorithms with Large Language Models16 Aug 2025
- 2025Protocols for Verifying Smooth Strategies in Bandits and Games8 Jul 2025
- 2025Expected Variational Inequalities25 Feb 2025
- 2025Learning and Computation of Phi-Equilibria at the Frontier of Tractability25 Feb 2025
- 2025Fixed Point Computation: Beating Brute Force with Smoothed Analysis18 Jan 2025
- 2024Computational Lower Bounds for Regret Minimization in Normal-Form Games4 Nov 2024
- 2024The complexity of approximate (coarse) correlated equilibrium for incomplete information games4 Jun 2024
12 newest of 29 All 29 (JSON)