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20242026
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cs.LG2026

Reformulate LLM Reinforcement Learning for Efficient Training under Black-box Discrepancy

Jiashun Liu, Runze Liu, Xu Wan +3

Reinforcement Learning (RL) has emerged as a pivotal post-training paradigm, yet it frequently suffers from unpredictable sub-optimum performance or even training collapses. Recent…

cs.LG2026

When RL Fails after SFT: Rejuvenating Model Plasticity for Robust SFT-to-RL Handoff

Runze Liu, Jiashun Liu, Xu Wan +2

Supervised Fine-Tuning (SFT) followed by Reinforcement Learning (RL) has become a standard pipeline for Large Language Model (LLM) post-training. SFT is expected to provide a usefu…

cs.LG2026

Local Guidance, Global Impact: Gaussian-Reshaped Trust Region Unlocks Behavior Transitions

Bingxu Liu, Jiashun Liu, Johan Obando-Ceron +5

While Proximal Policy Optimization (PPO) demonstrates strong performance in stationary settings, we show that its standard optimization paradigm struggles in continual and non-stat…

cs.LG2025

Learning Intractable Multimodal Policies with Reparameterization and Diversity Regularization

Ziqi Wang, Jiashun Liu, Ling Pan

Traditional continuous deep reinforcement learning (RL) algorithms employ deterministic or unimodal Gaussian actors, which cannot express complex multimodal decision distributions.…

cs.LG2025

Asymmetric Proximal Policy Optimization: mini-critics boost LLM reasoning

Jiashun Liu, Johan Obando-Ceron, Han Lu +7

Most recent RL for LLMs (RL4LLM) methods avoid explicit critics, replacing them with average advantage baselines. This shift is largely pragmatic: conventional value functions are…

cs.LG2025

Part II: ROLL Flash -- Accelerating RLVR and Agentic Training with Asynchrony

Han Lu, Zichen Liu, Shaopan Xiong +19

Synchronous Reinforcement Learning (RL) post-training has emerged as a crucial step for enhancing Large Language Models (LLMs) with diverse capabilities. However, many systems desi…