Research map / Optimization / Nonconvex and smooth optimization
Accelerated Regularized Learning in Finite N-Person Games
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Introduces "follow the accelerated leader" (FTXL), a Nesterov-style momentum version of regularized learning (FTRL/exponential weights) in finite games, proving superlinear local convergence to strict Nash equilibria under full, realization-based, and bandit feedback.
Problem
Regularized learning in games (FTRL, exponential weights) converges to strict Nash equilibria only at a geometric (linear) rate, and it is unknown whether Nesterov-style acceleration can be carried over to game-theoretic online learning.
Approach
Apply the continuous-time heavy-ball-with-vanishing-friction view of Nesterov's method to the score variables of FTRL, giving a second-order (payoff-momentum) learning scheme; with zero friction it is a discrete momentum update on scores whose mirror map gives strategies, achieving superlinear convergence to strict equilibria across feedback models.
Key results
- Continuous-time FTXL with logit best responses satisfies sup-norm distance to a strict NE bounded by exp(C - c t^2 / (2(γ+1))), a superlinear rate versus geometric rate for replicator dynamics.
- Discrete-time FTXL with full information achieves exp(C - c η² N(N-1)/2) = exp(-Θ(N²)) local convergence to strict NE.
- Superlinear rate is maintained with realization-based and bandit (importance-weighted) feedback with high probability, with degraded subleading terms (exponent 5/3 and 9/5 respectively).
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use FTXL instead of first-order regularized learning | Learning near strict Nash equilibria · Strict Nash equilibria | convergence rate: \exp(-\Theta(\nRuns)) -> \exp \parens[\big]{-\Theta(\cramped{\nRuns^{2}})} | Helped |
| Use FTXL with full-information feedback | FTXL · Strict Nash equilibria, full information | strategy error bound: \exp(-\Theta(\nRuns)) -> \exp \parens[\big]{-\Theta(\cramped{\nRuns^{2}})} | Helped |
| Use FTXL with realization-based feedback | FTXL · Strict Nash equilibria, realization-based feedback | strategy error bound: \exp \parens[\big]{-\Theta(\cramped{\nRuns^{2}})} | Helped |
| Use FTXL with bandit payoff feedback | FTXL · Strict Nash equilibria, bandit feedback | strategy error bound: \exp \parens[\big]{-\Theta(\cramped{\nRuns^{2}})} | Helped |
| Use bandit feedback instead of realization-based feedback | FTXL · Zero-sum and congestion games | convergence performance | Hurt |
| Use non-vanishing friction instead of zero friction (ablation) | FTXL · Single-player, two-action strict Nash game | strategy error decay rate: \sim \exp\parens*{\Const - \frac{\step^2\horizon^2}{2(\step\fr+1)}}; \sim \exp\parens*{\Const - \frac{\step}{\fr}\run} | Hurt |
| Use positive vanishing friction instead of zero friction (ablation) | Continuous-time FTXL · Strict Nash equilibria | convergence rate: \exp\parens*{\Const - \frac{\const\draft{t}^{2}}{2(\fr+1)}} | Hurt |
Surprising findings
- Zero friction is optimal among the vanishing-friction schemes studied; adding friction hinders the equilibrium convergence rate.
- Superlinear convergence is retained even under bandit payoff-based feedback, despite the method being second-order in time rather than space.
Limitations
- Results are local: finite games can have multiple strict equilibria, so only local convergence to strict NE is established.
- Bandit feedback introduces a bias-variance trade-off via explicit exploration, and the subleading term worsens with less information.
- Numerical validation is limited to a small 2-player zero-sum game and a 100-player congestion game.
Experimental setup
Metrics: distance to strict Nash equilibrium convergence rate
Baselines: FTRL / exponential weights replicator dynamics
Builds on: Nesterov's accelerated gradient follow the regularized leader replicator dynamics heavy ball with vanishing friction
Closest papers by meaning
- On the Rate of Convergence of Regularized Learning in Games: From Bandits and Uncertainty to Optimism and Beyond (NeurIPS 2021 · similarity 0.93)
- (Doubly) Exponential Lower Bounds for Follow the Regularized Leader in Potential Games (ICML 2026 · similarity 0.91)
- From Average-Iterate to Last-Iterate Convergence in Games: A Reduction and Its Applications (NeurIPS 2025 · similarity 0.91)
- The Equivalence of Dynamic and Strategic Stability under Regularized Learning in Games (NeurIPS 2023 · similarity 0.90)
- Learning from Delayed Feedback in Games via Extra Prediction (NeurIPS 2025 · similarity 0.89)
- Fast Last-Iterate Convergence of Learning in Games Requires Forgetful Algorithms (NeurIPS 2024 · similarity 0.89)
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