arXiv:2603.02216cs.LGcs.AI2026-03中稿 · ICLR被引 5

针对医疗对话信息不全难题,提出自适应树策略优化算法提升诊断准确率。

ATPO: Adaptive Tree Policy Optimization for Multi-Turn Medical Dialogue

  • 根据贝尔曼误差与动作值方差动态分配采样预算,增强不确定性状态的探索
  • 在三个公开数据集上,Qwen3-8B模型精度超越更大的GPT-4o(+0.92%)
  • 通过剪枝与异步搜索降低计算开销,适合高交互医疗场景应用

多轮医疗对话中有效获取信息对准确诊断至关重要,尤其在信息不完整时。由于用户-代理交互存在固有不确定性,我们将其建模为分层马尔可夫决策过程(H-MDP)。传统强化学习方法如组相对策略优化(GRPO)在长周期信用分配上表现不佳,而近端策略优化(PPO)在此类场景中价值估计不稳定。为此,我们提出一种新型不确定性感知的自适应树策略优化(ATPO)算法。该方法基于贝尔曼误差与动作值方差的综合度量,动态将采样预算分配给高不确定性状态,从而提升价值估计精度并促进更高效、多样化的探索。为缓解树状强化学习的高计算成本,引入两项关键优化:基于不确定性的剪枝机制以减少采样次数,以及利用键值缓存复用的异步搜索架构以最大化推理吞吐量。在三个公开医疗对话基准上的实验表明,该算法显著优于多个强基线模型,其中Qwen3-8B模型在准确率上超越更大的GPT-4o(+0.92%)。

原文摘要 · Abstract (English)

Effective information seeking in multi-turn medical dialogues is critical for accurate diagnosis, especially when dealing with incomplete information. Aligning Large Language Models (LLMs) for these interactive scenarios is challenging due to the uncertainty inherent in user-agent interactions, which we formulate as a Hierarchical Markov Decision Process (H-MDP). While conventional Reinforcement Learning (RL) methods like Group Relative Policy Optimization (GRPO) struggle with long-horizon credit assignment and Proximal Policy Optimization (PPO) suffers from unstable value estimation in this context, we propose a novel uncertainty-aware Adaptive Tree Policy Optimization (ATPO) algorithm. Our method adaptively allocates the rollout budget to states with high uncertainty, quantified by a composite metric of Bellman error and action-value variance. This strategy enables more accurate value estimation, while fostering more efficient and diverse exploration. To mitigate the high computational cost of tree-based RL, we introduce two key optimizations: an uncertainty-guided pruning mechanism to minimize the number of rollouts, and an asynchronous search architecture that leverages KV cache reuse to maximize inference throughput. Extensive experiments on three public medical dialogue benchmarks demonstrate that our algorithm significantly outperforms several strong baselines, culminating in Qwen3-8B model surpassing the much larger GPT-4o ($+0.92\%$ accuracy).

医疗对话强化学习大模型策略优化

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