Optimal last-iterate convergence in matrix games with bandit feedback using the log-barrier
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Abstract (arXiv)
We study the problem of learning minimax policies in zero-sum matrix games. Fiegel et al. (2025) recently showed that achieving last-iterate convergence in this setting is harder when the players are uncoupled, by proving a lower bound on the exploitability gap of Omega(t^{-1/4}). Some online mirror descent algorithms were proposed in the literature for this problem, but none have truly attained this rate yet. We show that the use of a log-barrier regularization, along with a dual-focused analysis, allows this O-tilde(t^{-1/4}) convergence with high-probability. We additionally extend our idea to the setting of extensive-form games, proving a bound with the same rate.
Key facts. Cited by 5 papers in the map (data through 14 Oct 2026). Builds on 4 of its 15 references that are in the map. First posted on arXiv 16 Apr 2026.
Builds on
4 of 15 references.
References · 4
- 2013Optimization, Learning, and Games with Predictable Sequencescited by 188
- 2021Last-iterate Convergence of Decentralized Optimistic Gradient Descent/Ascent in Infinite-horizon Competitive Markov Gamescited by 69
- 2023Uncoupled and Convergent Learning in Two-Player Zero-Sum Markov Games with Bandit Feedbackcited by 30
- 2018Let's be Honest: An Optimal No-Regret Framework for Zero-Sum Gamescited by 11
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Citing papers per year: 2026: 5.
5 papers.
- 2026Near-Optimal Last-Iterate Convergence for Zero-Sum Games with Bandit Feedback and Opponent Actionscited by 4
- 2026Minimax Last-Iterate Convergence in Matrix Games with Observed Actionscited by 1
- 2026Polylogarithmic Nash Regret in Matrix Games with Bandit Feedbackcited by 0
- 2026Fast Last-Iterate Convergence in Zero-Sum Markov Games with Bandit Feedbackcited by 0
- 2026Thompson Sampling for Learning in Zero-Sum Gamescited by 0
- 2026Thompson Sampling for Learning in Zero-Sum Games11 Oct 2026
- 2026Fast Last-Iterate Convergence in Zero-Sum Markov Games with Bandit Feedback5 Oct 2026
- 2026Polylogarithmic Nash Regret in Matrix Games with Bandit Feedback28 Sep 2026
- 2026Minimax Last-Iterate Convergence in Matrix Games with Observed Actions28 Sep 2026
- 2026Near-Optimal Last-Iterate Convergence for Zero-Sum Games with Bandit Feedback and Opponent Actions10 May 2026