Efficient Reinforcement Learning with Large Language Model Priors
Xue Yan, Yan Song, Xidong Feng, Mengyue Yang, Haifeng Zhang, Haitham, Bou Ammar, Jun Wang

TL;DR
This paper introduces a method to incorporate large language model priors into reinforcement learning, significantly enhancing sample efficiency and reducing exploration in complex sequential decision-making tasks.
Contribution
It presents a novel framework for integrating LLM priors into RL via Bayesian inference, improving efficiency and generalization across environments.
Findings
Reduces exploration by over 90% in offline RL scenarios
Enhances sample efficiency compared to traditional RL methods
Facilitates seamless integration of LLM priors into RL algorithms
Abstract
In sequential decision-making (SDM) tasks, methods like reinforcement learning (RL) and heuristic search have made notable advances in specific cases. However, they often require extensive exploration and face challenges in generalizing across diverse environments due to their limited grasp of the underlying decision dynamics. In contrast, large language models (LLMs) have recently emerged as powerful general-purpose tools, due to their capacity to maintain vast amounts of domain-specific knowledge. To harness this rich prior knowledge for efficiently solving complex SDM tasks, we propose treating LLMs as prior action distributions and integrating them into RL frameworks through Bayesian inference methods, making use of variational inference and direct posterior sampling. The proposed approaches facilitate the seamless incorporation of fixed LLM priors into both policy-based and…
Peer Reviews
Decision·ICLR 2025 Poster
1. This paper is clearly written and easy to follow. 2. The considered "incorporating the background knowledge of LLM into RL" is an interesting topic.
1. There are no convergence guarantees of sampling using LLM as prior for Exploration and Q-function update. Moreover, there is no guarantee that learning the Q-function as shown in Equation (7) will give us a conservative Q-function. 2. If the LLM can not provide a good prior, constraining the learned policy as shown in Equation (8) will result in sub-optimal policies. 3. The RL process has to query the LLM each time we update the policy, which is time-consuming and computation-consuming.
The paper is written very clearly with appropriate figures, well-formatted equations and more importantly lucid logical flow. The contributions of the paper are specified along with particular sections corresponding to individual contribution. Preliminaries provide enough details and are not overexplained. The core idea of the paper is pretty neat -- LLMs are trained on large amount of data and they have knowledge about tasks if not fine-grained controllability; this knowledge is useful to gui
Practicality of value based approaches: Although the value-based direct posterior sampling technique described in the paper is logically sound, I wonder about its practicality. Mainly, value-based approaches when applied to combinatorically large action spaces like text generation is practically infeasible. Hence, the paper's proposed method might be hard to apply beyond toy textual environments. Noticeably, these environments are designed to accept actions in a particular format or use rigorous
This paper tackles a very important topic: how to leverage LLMs into sequential decision-making tasks incorporating language. I enjoyed reading it. Performance improvements over considered baselines are impressive.
### Value-based version I am having trouble understanding how useful the value-based formulation is. What I mean is that, from my understanding, at inference time you need both the frozen LLM and the trained Q-network (which is a smaller LLM). This makes the approach quite expensive regarding memory. Regarding inference, it is also costly: the frozen LLM must provide k outputs before being able to use the Q-network LLM, for each step in the environment. A good comparative study here to motivate
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Taxonomy
TopicsSpeech and dialogue systems · Topic Modeling
MethodsVariational Inference
