Advances in Reinforcement Learning for Retrieval-Augmented Generation in Large Language Model

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Retrieval-augmented generation (RAG) enhances large language models (LLMs) by incorporating external information, but traditional fixed retrieval processes struggle to adapt to complex task requirements. In recent years, reinforcement learning (RL) has been increasingly applied to train LLMs to autonomously invoke search tools, driving RAG to evolve from the passive information acquisition of a fixed pipeline to a trustworthy retrieval system with autonomous decision-making capabilities. This paper reviews the representative studies on the combination of LLMs, RAG and RL in recent years. It focuses on analyzing the role of RL in dynamic retrieval, process rewards, query optimization, etc., and compares the connections and evolutionary relationships among different methods. The research findings show that RL has gradually expanded from simply improving the accuracy of the final answer to optimizing queries, multi-round search, process decision-making and trustworthy screening, providing new ideas for enhancing the active retrieval ability of RAG and improving the credibility of information.