Reinforcement learning

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

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arXiv AI
Oct 7

Stabilizing Off-Policy Training for Long-Horizon LLM Agent via Turn-Level Importance Sampling and Clipping-Triggered Normalization

The paper introduces SORL, a framework that stabilizes off‑policy reinforcement learning for long‑horizon large language model agents. It identifies two key instability sources—token‑level policy granularity mismatches and high‑variance off‑policy updates—and proposes turn‑level importance sampling and clipping‑triggered normalization to align optimization with multi‑turn interactions. Two instantiations, SO‑PPO and SO‑GRPO, are evaluated on open‑domain, multi‑hop, and medical QA benchmarks, as well as on asynchronous RL for mathematical reasoning, showing improved robustness without the need for early stopping or heuristic tuning.

By Chenliang Li, Adel Elmahdy, Alex Boyd, Zhongruo Wang, Siliang Zeng, Alfredo Garcia, Parminder Bhatia, Taha Kass-Hout, Cao Xiao, Mingyi Hong
arXiv AI
Oct 7

Guided Action Flow: Value-Guided Sampling for Frozen Vision-Language-Action Policies

arXiv:2607.02092v4 Announce Type: replace-cross Abstract: Reinforcement learning can improve vision-language-action (VLA) policies beyond supervised fine-tuning, although this typically involves furt...

By Liuhaichen Yang, Zhuang Jiang, Chenchao Sheng, Ningwei Bai, Qichen Yin, Hanbo Ma, Junkai Liu, Junkai Sun, Dongcheng Lyu, Yi Dong, Zezhi Tang
arXiv AI
Oct 7

Best-of-$N$ Guidance for Test-time Diffusion Alignment

The paper introduces Best‑of‑N Guidance (BoNG), a method that embeds the Best‑of‑N sampling principle directly into the reverse diffusion process of generative models. By performing online BoN selection over denoising particles and using the current best particle as a guidance signal, BoNG steers the particle population toward higher‑reward regions during generation. Empirical results show that BoNG outperforms both standard BoN and SMC across 36 comparisons, achieving the best performance in 29 cases and supporting multi‑output generation with significant speedup.

By Richard Lee Kim, Yeongmin Kim, Gyuwon Sim, Taekyu Kim, Minsang Park, Il-chul Moon
arXiv AI
Oct 7

Self-Referenced Social Preferences: Cooperation without Observing Others Rewards

The paper introduces self‑referenced social preferences, allowing agents to learn cooperative behavior without observing others’ private rewards. Each agent models its own reward, applies this model to observed transitions of other agents, and uses the resulting assessments to inform either the learning reward or policy updates. Experiments on three social‑dilemma environments show that agents can achieve cooperation and more equitable outcomes even when independent learners fail, with the best integration point depending on the type of social preference used.

By Mohamed Ayman Mohamed, Harshil Kotamreddy, Marcos Menon Jose
arXiv AI
Oct 7

Self-Retrospection Distillation: Turning Post-hoc Experiences into Prior Foresight

The paper introduces Self‑Retrospection Distillation (SRD), a method that uses post‑hoc trajectories to supervise foresight predictions made before an agent acts. SRD distills information from completed rollouts into trajectory‑blind predictions, enabling the agent to anticipate useful actions and avoid pitfalls without requiring explicit foresight at inference time. Experiments on ten tool‑integrated reasoning and long‑horizon tasks show that SRD improves performance by up to 24.2 percentage points, especially when reward signals are scarce or uniform across rollouts.

By Haoxiang Zhang, Qinglin Chen, Hiroaki Hayashi, Zhuofeng Li, Siming Zhang, Jiaxin Zhang, Jixuan Chen, Fang Wu, Pan Lu, Silvio Savarese, Julian McAuley, Chien-Sheng Wu
Hugging Face Trending Papers
Oct 5

Dynamic Minimax Regret Optimization for Robust LLM Post-Training

The paper introduces DUCB-OGD, an algorithm that couples a Discounted Upper‑Confidence‑Bound sampler with Online Gradient Descent to address dynamic minimax regret in robust large‑language‑model post‑training. It operates under instantaneous mini‑batch‑only bandit feedback, tracking worst‑source performance without re‑evaluating historical data. Experiments on fine‑tuning, preference optimization, and reinforcement learning demonstrate that DUCB‑OGD improves worst‑group robustness with negligible computational overhead.

Hugging Face Trending Papers
Oct 5

Evolving in Thought Space: Training a Small Model at Test Time Unlocks Better Discoveries

The paper introduces Guidance‑TTT, a method that separates strategic planning from execution in test‑time training for large language models. A small guidance model is trained at test time to propose high‑level changes, while a frozen, larger execution model implements these changes, reducing the cost of maintaining gradients and optimizer states. Guidance‑TTT achieves strong results across four domains—combinatorial optimization, heuristic programming, machine learning, and GPU kernel optimization—outperforming prior work and matching state‑of‑the‑art leaderboard scores.