Reinforcement learning

Policy optimisation, reward modelling and RLHF — how models are trained by feedback rather than by labels.

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arXiv Machine Learning
19h ago

MCLR: Improving Conditional Modeling via Inter-Class Likelihood-Ratio Maximization and Unifying Classifier-Free Guidance with Alignment Objectives

arXiv:2603.22364v4 Announce Type: replace Abstract: Diffusion models achieve strong generative performance but often rely on classifier-free guidance (CFG), an inference-time intervention that modifi...

By Xiang Li, Yixuan Jia, Xiao Li, Jeffrey A. Fessler, Rongrong Wang, Qing Qu
arXiv Computation and Language
19h ago

ECHO: Emergent Common-Mode Hidden Offsets Drive Vocabulary Collapse in Preference Optimization

arXiv:2610.29410v1 Announce Type: new Abstract: Preference optimization can improve every ranking metric while building a hidden, shared representation shift that the relative loss barely sees, one t...

By Yun Li, Ehsan Javanmardi, Simon Thompson, Jiachen Gong, Qunli Zhang, Zifan Zeng, Shiming Liu, Peng Wang, Zixuan Guo, Manabu Tsukada
arXiv Computation and Language
19h ago

Uni-Mem: Learning a Long-Horizon Agentic Memory Manager with Unified Online Policy Optimization

arXiv:2610.29671v1 Announce Type: new Abstract: Long-term agent memory is shifting from predefined workflows toward learnable policies for memory construction and retrieval. Existing learning-based m...

By Zhiqian Xia, Jielong Tang, Ling-An Zeng, Shixiong Kai, Rong Yao, Hao Kong, Xiao Dong, Wei Wang, Mingxuan Yuan, Siyu Xia, Haifeng Xia
arXiv Computation and Language
19h ago

HybridResearcher: Bridging the Structured-Unstructured Boundary for Deep Research Agents

arXiv:2610.24899v2 Announce Type: replace-cross Abstract: While LLM agents are increasingly capable of gathering and synthesizing evidence from a single homogeneous source, such as structured tables...

By Soyoung Yoon, Peiran Xu, Han Wang, Ruofan Wu, Xiaodong Yu, Feng Yan, Mohit Bansal, Debiao Li, Seung-Won Hwang, Yuxiong He, Zhewei Yao
arXiv Machine Learning
1d ago

Continuous-Time Policy Gradient from Discrete Data: Convergence Analysis and Model-Free Algorithms

The paper introduces a continuous‑time policy gradient framework that works with discrete observation data. It derives performance difference lemmas and policy gradient formulas for randomized and parametrized policies, proving exponential convergence for an entropy‑regularized policy flow and providing explicit convergence bounds for discrete updates. By integrating with PhiBE, the authors create model‑free actor‑critic algorithms that maintain the continuous‑time structure, and demonstrate their effectiveness on both linear‑quadratic and nonlinear robotic control tasks.

By Martin Hernandez, Xinyan Qing, Mo Zhou, Yuhua Zhu
arXiv Machine Learning
1d ago

Hybrid Belief Reinforcement Learning for Efficient Coordinated Spatial Exploration

The paper introduces Hybrid Belief Reinforcement Learning (HBRL), a two‑phase framework for coordinating multiple autonomous agents in spatial exploration tasks. In phase one, agents build spatial beliefs via a Log‑Gaussian Cox Process and plan information‑driven trajectories using a Pathwise Mutual Information planner; in phase two, a Soft Actor‑Critic policy is warm‑started through dual‑channel knowledge transfer that incorporates belief states and replay‑buffer demonstrations. Experiments on UAV wireless service provisioning and NYC taxi demand sensing show significant performance gains, with the dual‑channel transfer outperforming single‑channel approaches.

By Danish Rizvi, David Boyle
arXiv Machine Learning
1d ago

How Data Scales in Agentic Reinforcement Learning: Laws and Synthesis Strategies

The paper investigates how data should be scaled in agentic reinforcement learning, where data is now a structured design space of tasks, environments, and trajectories. By fitting per‑axis scaling laws across various large language models and RL algorithms, the authors find that environment diversity has the strongest impact, followed by task and trajectory diversity. Using these laws, they price synthesis methods, identify critical synthetic‑to‑real ratios, and formulate a compute‑optimal budget allocation that can improve efficiency by up to 1.7× compared to the common practice of scaling trajectories alone.

By Bowei He, Yankai Chen, Xiaokun Zhang, Changjiang Han, Ye Yuan, Chong Li, Xue Liu
arXiv Computation and Language
1d ago

Reward Misspecification Degrades Chain-of-Thought Monitorability

The paper investigates how reward misspecification in reinforcement learning harms the ability to monitor chain-of-thought (CoT) reasoning in language models. By creating a testbed with true and misspecified rewards, the authors show that models can hack the reward while still producing CoTs that appear aligned, leading to low monitorability. They propose a mitigation strategy that collects diverse reward rollouts, infers a reward description with a language model, and injects this description into the input, improving monitorability by up to 42% absolute across models and tasks.

By Tianyi Lorena Yan, John Hewitt
arXiv Computer Vision
1d ago

RoboJudge: Multimodal Language Models as Judges for Embodied Video Generation

The paper introduces RoboJudge, a multimodal language model trained to evaluate embodied video generation. It presents RoboJudge-Bench, a benchmark of 800 human‑annotated videos assessing Physical Adherence and Instruction Alignment, and RoboJudge-Train, a 12K‑video dataset with human‑verified scores and rationales. Fine‑tuned on this data, RoboJudge‑9B achieves the highest agreement with human judgments, outperforming existing models and improving performance on external physics benchmarks.

By Siyuan Ma, Yu Qi, Cheng Ye, Ruotian Peng, Xinyi Xu, Zitiantao Lin, Zedong Cai, Yijian Huang, Weiyang Liu, Siyuan Wang, Yandong Wen
arXiv AI
1d ago

Vulnerability Analysis for Safe Multi-Agent Reinforcement

The paper examines inference‑time observation attacks on Safe Multi‑Agent Reinforcement Learning (SMARL), where an adversary perturbs observations of some agents to alter their actions. It introduces the MinMax Attack framework, which jointly selects adversarial target actions for compromised agents while considering the cooperative resistance of benign agents. The authors derive a bound on the induced safety cost and show through experiments that MinMax Attack causes higher safety costs than existing baselines while maintaining task reward, thus improving attack effectiveness and stealthiness.

By Taozheng Zhu, Shixiong Jiang, Fanxin Kong