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Jonathan Daniel Chang

7 accepted papers

2025

$Q\sharp$: Provably Optimal Distributional RL for LLM Post-Training

NeurIPS 2025poster

Reinforcement learning (RL) post-training is crucial for LLM alignment and reasoning, but existing policy-based methods, such as PPO and DPO, can fall short of fixing shortcuts inherited from pre-training. In this work, we introduce $Q\sharp$, a value-based algorithm for KL-regularized RL that guide…

Cited by 0SourcecodeScholar
2025

Regressing the Relative Future: Efficient Policy Optimization for Multi-turn RLHF

ICLR 2025poster

Large Language Models (LLMs) have achieved remarkable success at tasks like summarization that involve a single turn of interaction. However, they can still struggle with multi-turn tasks like dialogue that require long-term planning. Previous works on multi-turn dialogue extend single-turn reinforc…

2025

Value-Guided Search for Efficient Chain-of-Thought Reasoning

NeurIPS 2025poster

In this paper, we propose a simple and efficient method for value model training on long-context reasoning traces. Compared to existing process reward models (PRMs), our method does not require a fine-grained notion of ``step,'' which is difficult to define for long-context reasoning models. By coll…

Cited by 0SourcecodeScholar
2024

Adversarial Imitation Learning via Boosting

ICLR 2024poster

Adversarial imitation learning (AIL) has stood out as a dominant framework across various imitation learning (IL) applications, with Discriminator Actor Critic (DAC) demonstrating the effectiveness of off-policy learning algorithms in improving sample efficiency and scalability to higher-dimensional…

Cited by 2SourcePDFScholar
2024

REBEL: Reinforcement Learning via Regressing Relative Rewards

NeurIPS 2024poster

While originally developed for continuous control problems, Proximal Policy Optimization (PPO) has emerged as the work-horse of a variety of reinforcement learning (RL) applications, including the fine-tuning of generative models. Unfortunately, PPO requires multiple heuristics to enable stable conv…

2021

Mitigating Covariate Shift in Imitation Learning via Offline Data With Partial Coverage

NeurIPS 2021poster

This paper studies offline Imitation Learning (IL) where an agent learns to imitate an expert demonstrator without additional online environment interactions. Instead, the learner is presented with a static offline dataset of state-action-next state triples from a potentially less proficient behavio…

2021

MobILE: Model-Based Imitation Learning From Observation Alone

NeurIPS 2021poster

This paper studies Imitation Learning from Observations alone (ILFO) where the learner is presented with expert demonstrations that consist only of states visited by an expert (without access to actions taken by the expert). We present a provably efficient model-based framework MobILE to solve the I…