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Shengpu Tang

5 accepted papers

2026

Slow-Fast Policy Optimization: Reposition-Before-Update for LLM Reasoning

ICLR 2026poster

Reinforcement learning (RL) has become central to enhancing reasoning in large language models (LLMs). Yet on-policy algorithms such as Group Relative Policy Optimization (GRPO) often suffer in early training: noisy gradients from low-quality rollouts lead to unstable updates and inefficient explora…

Cited by 0SourcecodeScholar
2023

Counterfactual-Augmented Importance Sampling for Semi-Offline Policy Evaluation

NeurIPS 2023poster

In applying reinforcement learning (RL) to high-stakes domains, quantitative and qualitative evaluation using observational data can help practitioners understand the generalization performance of new policies. However, this type of off-policy evaluation (OPE) is inherently limited since offline dat…

2022

Leveraging Factored Action Spaces for Efficient Offline Reinforcement Learning in Healthcare

NeurIPS 2022accept

Many reinforcement learning (RL) applications have combinatorial action spaces, where each action is a composition of sub-actions. A standard RL approach ignores this inherent factorization structure, resulting in a potential failure to make meaningful inferences about rarely observed sub-action com…

2020

Clinician-in-the-Loop Decision Making: Reinforcement Learning with Near-Optimal Set-Valued Policies

ICML 2020poster

Standard reinforcement learning (RL) aims to find an optimal policy that identifies the best action for each state. However, in healthcare settings, many actions may be near-equivalent with respect to the reward (e.g., survival). We consider an alternative objective – learning set-valued policies to…