Reinforcement learning

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

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arXiv AI
Sep 23

Taming CoT Obfuscation in VLMs: From Mechanistic Evidence to Activation Enforcement

The paper investigates how reinforcement learning can unintentionally obscure the chain‑of‑thought (CoT) reasoning in vision‑language models, making their internal reasoning less traceable. By analyzing activation patterns, the authors show that template‑associated activations become less distinguishable during RL and that targeted interventions can mitigate this effect. They introduce TAME, a method that uses sparse autoencoders to suppress these problematic activations while still encouraging accurate behavior, achieving significant gains in CoT monitorability across multiple datasets and model families.

By Xutao Mao, Jianing Zhu, Jinman Zhao, Tongliang Liu, Xiaowen Chu, Cong Wang, Bo Han
arXiv Machine Learning
Sep 23

WeightBridge: An Efficient Weight Transfer Library for Reinforcement Learning

WeightBridge is a lightweight library that streamlines weight transfer between trainers and rollout generators in reinforcement learning systems, particularly for large language models. It automatically maps trainer and rollout weight layouts, then performs redundancy‑free, load‑balanced transfers while supporting various synchronization modes. Experiments show that WeightBridge can cut GPU stall time by up to 42× compared to leading open‑source RL frameworks, and it was easily integrated into two different frameworks by a coding agent.

By Xuanlin Jiang, Samuel Hsia, Michael Kuchnik, Zachary DeVito, Minlan Yu, Carole-Jean Wu
arXiv Computer Vision
Sep 23

KwaiMind Technical Report

KwaiMind is a commercial image editing system that combines general editing capabilities with e-commerce specialization. It uses an agent-based data engine with 1.8 million editing pairs and a multimodal diffusion transformer trained through pre‑training, fine‑tuning, preference optimization, and online reinforcement learning. The system is guided by a vision‑language judge and specialized rewards for click‑through rate, text rendering, and product consistency, and it achieves top scores on ImgEdit, GEdit, REDEdit, and the new Ecom‑Bench, while improving predicted and actual CTR in offline and online experiments.

By Junlong Wu, Zijun Li, Yuting Hu, Jia Sun, Pengcheng Wei, Yimin Zhou, Honglie Wang, Huaiqing Wang, Dewen Fan, Fei Zuo, Haixuan Gao, Lihui Peng, Tingxuan She, Yuqing Li, Boheng Zhang, Fan Yang, Wenwu Ou
arXiv Computer Vision
Sep 23

Video-HopChain: Multi-Hop Questions and Confidence-Gated Exploration for Video Reasoning Models

Video-HopChain introduces a new dataset of 22,550 multi‑hop video questions over 13,378 videos, each question consisting of three to six yes/no sub‑questions whose integer answers sum to a verifiable reward. Training a Qwen3‑VL‑8B model with GRPO on this dataset improves performance across eight video‑understanding benchmarks from 55.4 to 57.9, and the addition of Confidence‑Gated Exploration (CGE) raises the mean to 59.3. The authors release the dataset, checkpoint, and training code for further research.

By Trung Nguyen Quang, Yuhao Dong, Shuo Sun, Shuai Liu, Shulin Tian, Kim-Hui Yap, Ziwei Liu
arXiv Machine Learning
Sep 22

Beyond Task Completion: Training Capable and Safe Computer-Use Agents

The paper introduces SCOPE, a method that post‑trains computer‑use agents to balance task completion with safety by conditioning actions on environmental risk. It combines supervised fine‑tuning on three trajectory types—capability demonstrations, safe continuations, and explicit refusals—followed by reinforcement learning to improve performance. Experiments starting from Qwen3.5‑9B show that SCOPE‑RL achieves high task success and attack‑avoidance rates, outperforming other agents on OSWorld and OS‑BLIND benchmarks.

By Zeyu Kang, Zhenyun Yin, Yang Zhang, Shan He, Shanzhe Lei, Yanjiu Zhong, Xinquan Chen, Yuhong Wang
arXiv Machine Learning
Sep 22

The Neural Forcing for Three-Dimensional Incompressible Navier-Stokes finite time blowup

The paper introduces a two-part neural framework for generating and analyzing forced three-dimensional incompressible Navier–Stokes flow. Part I focuses on a physics‑informed neural model that produces structured external‑force trajectories, optimizes them via differentiable PDE rollouts or PPO‑Clip, and validates selected forcings through fixed‑force replay. Part II provides a mathematical certification layer that separates neural candidate discovery from continuum analysis, derives integrated reciprocal‑vorticity criteria implying Riccati‑type growth and finite‑time loss of smooth continuation, and establishes a conditional positive‑probability closure for a nondegenerate neural output law, completing the proof at the continuum level.

By Beibei Li
arXiv Machine Learning
Sep 22

Reinforcement Learning Inspired Black-box Adversarial Attacks for Computer Vision

The paper introduces RIBA, a reinforcement‑learning inspired black‑box adversarial attack that generates perturbations for neural networks with fewer queries than existing methods. RIBA achieves a 25.4% reduction in median queries on ResNet‑18/Cifar10 and a 22.5% reduction on Vit‑B/16/ImageNet, while matching white‑box attack performance on an adversarially trained model.

By Florian Krone, Elena Hoemann, Sven Hallerbach
arXiv Machine Learning
Sep 22

RLVR is a Kernel, Not a Function: Statistical Inference for pass@$k$ Crossovers

The paper argues that the observed crossover in pass@$k$ performance between reinforcement learning with verifiable rewards (RLVR) and its base model is not always statistically confirmed. By constructing confidence bands across sampling budgets and performing power analyses, the authors show that many reported crossovers lack statistical support and that more prompts can improve detection more than more answers per prompt. They further demonstrate that RLVR’s effect on a prompt is better described as a conditional distribution (a Markov kernel) rather than a single curve, allowing predictions of crossovers in new data and clarifying how losses on difficult prompts can overturn early gains.

By Chen Yang, Xianyang Zhang, Jun Chen
arXiv Computer Vision
Sep 22

Monitorable Chart Reasoning Agents via Verifiable Process Rewards

The paper introduces Chart‑RVR, a reinforcement‑learning framework that trains chart‑reasoning agents to produce monitorable, verifiable outputs. It decomposes reasoning into three auditable stages—Structure, Evidence, and Derivation—allowing stakeholders to trace how the model reads the chart, extracts data, and computes the answer. Experiments on six benchmarks show that Chart‑RVR matches or exceeds state‑of‑the‑art accuracy while delivering rationales that are far more verifiable and evidence‑grounded than existing methods.

By Sanchit Sinha, Oana Frunza, Kashif Rasul, Aidong Zhang