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Stephen Zhao

4 accepted papers

2025

Reducing the Probability of Undesirable Outputs in Language Models Using Probabilistic Inference

NeurIPS 2025poster

Reinforcement learning (RL) has become a predominant technique to align language models (LMs) with human preferences or promote outputs which are deemed to be desirable by a given reward function. Standard RL approaches optimize average reward, while methods explicitly focused on reducing the probab…

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2024

Probabilistic Inference in Language Models via Twisted Sequential Monte Carlo

ICML 2024oral

Numerous capability and safety techniques of Large Language Models (LLMs), including RLHF, automated red-teaming, prompt engineering, and infilling, can be cast as sampling from an unnormalized target distribution defined by a given reward or potential function over the full sequence. In this work,…

2022

Proximal Learning With Opponent-Learning Awareness

NeurIPS 2022accept

Learning With Opponent-Learning Awareness (LOLA) (Foerster et al. [2018a]) is a multi-agent reinforcement learning algorithm that typically learns reciprocity-based cooperation in partially competitive environments. However, LOLA often fails to learn such behaviour on more complex policy spaces para…

2020

Maximum Entropy Gain Exploration for Long Horizon Multi-goal Reinforcement Learning

ICML 2020poster

What goals should a multi-goal reinforcement learning agent pursue during training in long-horizon tasks? When the desired (test time) goal distribution is too distant to offer a useful learning signal, we argue that the agent should not pursue unobtainable goals. Instead, it should set its own intr…