Publications

2026

Revisiting DAgger in the Era of LLM-Agents

Preprint

Changhao Li, Rushi Qiang, Jiawei Huang, Chenxiao Gao, Chao Zhang, Niao He, Bo Dai

Summary
  • We revisit DAgger for multi-turn language-model agents, combining student–teacher rollouts with teacher-provided supervision to address covariate shift while retaining dense learning signals.
  • On SWE-bench Verified, this approach improves over the strongest post-training baseline by 3.9 points for 4B models and 3.6 points for 8B models.

Exploration-Driven Optimization for Test-Time Large Language Model Reasoning

TMLR 2026

Changhao Li, Yuchen Zhuang, Chenxiao Gao, Haotian Sun, Rushi Qiang, Chao Zhang, Bo Dai

Summary
  • Exploration-Driven Optimization (EDO) incorporates exploration incentives into iterative DPO and GRPO, preserving solution diversity for inference-time reasoning.
  • EDO improves reasoning on in-distribution and out-of-distribution benchmarks while maintaining model entropy and stabilizing reinforcement learning against over-optimization.

FlowRL: A Taxonomy and Modular Framework for Reinforcement Learning with Diffusion Policies

RLC 2026

Chenxiao Gao, Edward Chen, Tianyi Chen, Bo Dai

Summary
  • We organize the fast-growing landscape of RL with diffusion and flow policies into a unified taxonomy, clarifying the design choices behind existing algorithms.
  • We release a modular, JAX-based toolkit with JIT-compiled training and standardized benchmarks, making algorithms easy to compose, compare, and select across generative-modeling and robotics tasks.

GeMPO: Generalized Measure Matching for Online Diffusion Reinforcement Learning

Preprint

Haitong Ma, Chenxiao Gao, Tianyi Chen, Na Li, Bo Dai

Summary
  • We cast online diffusion RL through a measure-matching lens, generalizing the reweighting scheme from softmax to general monotonic functions.
  • By constructing a virtual target policy and minimizing divergence via reweighted flow matching, GeMPO enables flexible weight design and justifies negative reweighting that actively repels the policy from suboptimal actions.

2025

Spectral Representation-based Reinforcement Learning

JMLR (accepted)

Chenxiao Gao, Haotian Sun, Na Li, Dale Schuurmans, Bo Dai

Summary
  • We derive spectral representations from a decomposition of the transition operator, yielding an effective abstraction of the system dynamics with a clear theoretical characterization for downstream policy optimization.
  • The framework covers latent-variable and energy-based dynamics, extends to POMDPs, and matches or exceeds strong baselines on 20+ DeepMind Control Suite tasks.
Spectral Representation-based Reinforcement Learning — method overview

Kimi K2: Open Agentic Intelligence

Tech Report

Kimi Team (incl. Chenxiao Gao)

Summary
  • Kimi K2 is a 1T-parameter (32B active) mixture-of-experts model trained with the MuonClip optimizer for stable large-scale pre-training, achieving strong agentic and coding results (e.g., 65.8 on SWE-Bench Verified).
  • As part of the Kimi Team during my internship at Moonshot.AI, I worked on strengthening the model’s interactive tool-use capability across agent scaffolding, supervised fine-tuning, and reinforcement learning.

Behavior-Regularized Diffusion Policy Optimization for Offline Reinforcement Learning

ICML 2025

Chenxiao Gao, Chenyang Wu, Mingjun Cao, Chenjun Xiao, Yang Yu, Zongzhang Zhang

Summary
  • We Introduce pathwise KL to estimate and control the divergences between two diffusion policies;
  • Leveraging pathwise KL, we propose an actor-critic framework with two-time-scale temporal difference learning to efficiently optimize diffusion policies with behavior regularization.
Behavior-Regularized Diffusion Policy Optimization for Offline Reinforcement Learning — method overview

Reinforced In-Context Black-Box Optimization

IJCAI 2025

Lei Song*, Chenxiao Gao*, Ke Xue, Chenyang Wu, Dong Li, Jianye Hao, Zongzhang Zhang, Chao Qian

Summary
  • RIBBO distills and reinforces existing black-box optimization algorithms by fitting regret augmented learning histories of the behavior algorithms.
  • By specifying a suitable regret-to-go, RIBBO generate better query decisions by auto-regressively predicting the next points.
Reinforced In-Context Black-Box Optimization — method overview

2024

Diffusion Spectral Representation for Reinforcement Learning

NeurIPS 2024

Chenxiao Gao*, Dmitry Shribak*, Yitong Li, Chenjun Xiao, Bo Dai

Summary
  • We leverages the flexibility of diffusion models and extract spectral representations (Diff-SR) that capture the dynamics structure.
  • Diff-SR is able to represent the value function of any policy sufficiently, paving the way for efficient planning and exploration for downstream RL optimization.
Diffusion Spectral Representation for Reinforcement Learning — method overview

Hindsight Preference Learning for Offline Preference-based Reinforcement Learning

Preprint

Chenxiao Gao, Shengjun Fang, Chenjun Xiao, Yang Yu, Zongzhang Zhang

Summary
  • We identified shortages of the widely used preference modeling method in existing PbRL settings.
  • HPL leverages the vast unlabeled dataset to facilitate credit assignment, providing robust and advantageous rewards for downsteam RL optimization.
Hindsight Preference Learning for Offline Preference-based Reinforcement Learning — method overview

Efficient and Stable Offline-to-online Reinforcement Learning via Continual Policy Revitalization

IJCAI 2024

Rui Kong, Chenyang Wu, Chenxiao Gao, Yang Yu, Zongzhang Zhang

Summary
  • We identify two pain points in offline-to-online reinforcement learning: 1) value overestimation causes fluctuations during learning, and 2) the primacy bias hinders the policy from further improvement.
  • With the proposed Continual Policy Revitalization, we can fine-tune pret-rained policies efficiently and stably.
Efficient and Stable Offline-to-online Reinforcement Learning via Continual Policy Revitalization — method overview

Policy Rehearsing: Training Generalizable Policies for Reinforcement Learning

ICLR 2024

Chengxing Jia*, Chenxiao Gao*, Hao Yin, Fuxiang Zhang, Xiong-Hui Chen, Tian Xu, Lei Yuan, Zongzhang Zhang, Yang Yu, Zhi-Hua Zhou

Summary
  • We explore the idea of rehearsal for offline reinforcement learning, which generates diverse while eligible dynamics models using extremely limited amount of data and optimizes an contextual policy with the generated models.
  • By recognizing the context, the policy is able to generalize to the environment at hand during the online stage.
Policy Rehearsing: Training Generalizable Policies for Reinforcement Learning — method overview

Disentangling Policy from Offline Task Rpresentation Learning via Adversarial Data Augmentation

AAMAS 2024

Chengxing Jia, Fuxiang Zhang, Yi-Chen Li, Chenxiao Gao, Xu-Hui Liu, Lei Yuan, Zongzhang Zhang, Yang Yu.

Summary
  • Learned task representations from previous OMRL methods tend to correlate spuriously with the behavior policy instead of the task.
  • We disentangle the effect of behavior policies from representation learning by adversarial data augmentation.
Disentangling Policy from Offline Task Rpresentation Learning via Adversarial Data Augmentation — method overview

Generalizable Task Representation Learning for Offline Meta-Reinforcement Learning with Data Limitations

AAAI 2024

Renzhe Zhou, Chenxiao Gao, Zongzhang Zhang, Yang Yu

Summary
  • Real-world RL applications are with data limitations, such as limited tasks and limited behavior diversity.
  • We develop GENTLE, a simple yet effective task representation learning method to extract generalizable and accurate task representations from offline contextual datasets.
Generalizable Task Representation Learning for Offline Meta-Reinforcement Learning with Data Limitations — method overview