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arXiv 2407.20109cs.LGcs.AI
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Diffusion-DICE:面向离线强化学习的样本内扩散引导

Diffusion-DICE: In-Sample Diffusion Guidance for Offline Reinforcement Learning

Shanghai Jiao Tong University(上海交通大学);UT Austin(德克萨斯大学奥斯汀分校);Tsinghua University(清华大学)

Liyuan Mao, Haoran Xu, Xianyuan Zhan, Weinan Zhang, Amy Zhang

AI总结:

本研究提出离线强化学习方法Diffusion-DICE,将DICE方法视为分布变换,用扩散模型实现该变换,通过样本内学习引导项并采用先引导后选择范式,解决了以往扩散方法的误差问题,在基准测试中表现优异。

摘要:

分布校正估计(DIstribution Correction Estimation,DICE)方法的一个重要特性是,其求解结果为优化策略与数据收集策略之间的最优平稳分布比率。在本研究中,我们证明基于DICE的方法可被视为从行为分布到最优策略分布的一种变换。基于此,我们提出了一种新方法Diffusion-DICE,该方法利用扩散模型直接执行这一变换。我们发现最优策略的得分函数可分解为两项:行为策略的得分函数,以及依赖于最优分布比率的引导项梯度。第一项可通过在数据集上训练的扩散模型获得,我们还提出了一种样本内学习目标来学习第二项。由于最优策略分布中存在多模态特性,Diffusion-DICE中的变换可能会导向这些局部最优模态,因此我们生成若干候选动作并从中精心筛选,以逼近全局最优。与所有其他基于扩散的离线强化学习方法不同,Diffusion-DICE的“先引导后选择”范式仅使用样本内动作进行训练,能将价值函数中的误差利用程度降至最低。我们通过一个教学性玩具示例展示了以往基于扩散的方法因利用这些误差而无法生成最优动作的问题,以及Diffusion-DICE如何成功规避该问题。随后我们在基准数据集上开展了大量实验,证明了Diffusion-DICE的优异性能。项目页面:https://ryanxhr.github.io/Diffusion-DICE/。

英文摘要:

One important property of DIstribution Correction Estimation (DICE) methods is that the solution is the optimal stationary distribution ratio between the optimized and data collection policy. In this work, we show that DICE-based methods can be viewed as a transformation from the behavior distribution to the optimal policy distribution. Based on this, we propose a novel approach, Diffusion-DICE, that directly performs this transformation using diffusion models. We find that the optimal policy's score function can be decomposed into two terms: the behavior policy's score function and the gradient of a guidance term which depends on the optimal distribution ratio. The first term can be obtained from a diffusion model trained on the dataset and we propose an in-sample learning objective to learn the second term. Due to the multi-modality contained in the optimal policy distribution, the transformation in Diffusion-DICE may guide towards those local-optimal modes. We thus generate a few candidate actions and carefully select from them to approach global-optimum. Different from all other diffusion-based offline RL methods, the guide-then-select paradigm in Diffusion-DICE only uses in-sample actions for training and brings minimal error exploitation in the value function. We use a didatic toycase example to show how previous diffusion-based methods fail to generate optimal actions due to leveraging these errors and how Diffusion-DICE successfully avoids that. We then conduct extensive experiments on benchmark datasets to show the strong performance of Diffusion-DICE. Project page at https://ryanxhr.github.io/Diffusion-DICE/.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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