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Sample Efficient Reinforcement Learning with Partial Dynamics Knowledge
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Proposes UCB-f, an optimistic Q-learning method for finite episodic MDPs with additive disturbance dynamics that uses known or approximate dynamics f to propagate Q-updates to all state-action pairs, yielding sqrt(T) regret independent of S and A.
Problem
Sample complexity of online RL when partial knowledge of the system dynamics (an additive disturbance model S_{h+1}=f(S_h,A_h)+W_h) is available, with known or approximate f.
Approach
Use the known (or approximate) dynamics f to simulate Q-learning updates for all state-action pairs from each observed disturbance w_h = s_{h+1} - f(s_h,a_h), combined with a rescaled learning rate alpha_t=(H+1)/(H+t) and optimism bonuses, so regret does not scale with S and A when f is exact.
Key results
- With exact f, the algorithm achieves regret O~(sqrt(H^6 T)) with no dependence on S and A, versus O~(sqrt(H^2 SAT)) for prior Q-learning methods.
- With an approximate f_hat (||f_hat - f||_inf <= zeta/2), the regret adds a linear term O(L zeta H T) and the learned policy is (eps + O(L zeta H^2))-optimal.
- Empirically on random MDPs, UCB-f converges to the optimal policy with zeta=0 at a rate not affected by increasing S and A, while UCB-H and UCBVI slow down as S and A grow.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use known dynamics structure f in UCB-f rather than problem-agnostic Q-learning | UCB-f · Finite episodic MDPs | regret | Helped |
| Use UCB-f with the true function f instead of a noisy estimate | UCB-f · Randomly generated MDPs | suboptimality gap | Helped |
| Increase state and action cardinalities | UCB-f · Randomly generated MDPs | convergence time | No clear effect |
| Increase state and action cardinalities | UCB-H and UCBVI · Randomly generated MDPs | convergence time | Hurt |
| Use a noisy estimate $\hat{f}$ instead of the true function f | UCB-f · Randomly generated MDPs | suboptimality gap: $\mathcal{O}(L\zeta H^2)$ | Hurt |
Limitations
- Linear zeta*T regret term is unavoidable under persistent approximation error f_hat != f.
- Horizon dependence H^6 (or H^7 in the policy bound) is not sharp.
- Analysis restricted to tabular finite episodic MDPs with additive disturbances; value-function approximation and continuous spaces are left to future work.
Experimental setup
Datasets: randomly generated MDPs
Benchmarks: randomly generated MDPs (S=25, A in {2,4,8}, H in {5,10})
Metrics: regret per episode (suboptimality gap)
Baselines: UCB-H UCBVI
Builds on: UCB-H UCBVI Q-learning
Closest papers by meaning
- The Sample Complexity of Online Reinforcement Learning: A Multi-model Perspective (ICLR 2026 · similarity 0.93)
- Tightening the Dependence on Horizon in the Sample Complexity of Q-Learning (ICML 2021 · similarity 0.92)
- Non-Asymptotic Best Policy Identification Guarantees in Online Reinforcement Learning (NeurIPS 2026 · similarity 0.89)
- Sample Complexity of Distributionally Robust Average-Reward Reinforcement Learning (NeurIPS 2025 · similarity 0.89)
- On the Complexity of Offline Reinforcement Learning with Q*-Approximation and Partial Coverage (NeurIPS 2026 · similarity 0.88)
- A Nearly Optimal and Low-Switching Algorithm for Reinforcement Learning with General Function Approximation (NeurIPS 2024 · similarity 0.88)
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