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arXiv 2102.13045cs.LGcs.AI
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迭代边界MDP:通过不可解释的方法学习可解释的策略

Iterative Bounding MDPs: Learning Interpretable Policies via Non-Interpretable Methods

Carnegie Mellon University(卡内基梅隆大学)

Nicholay Topin, Stephanie Milani, Fei Fang, Manuela Veloso

摘要:

当前在可解释强化学习中的工作通常以状态空间上的决策树的形式产生策略。这些策略可用于正式的安全验证、代理行为预测和重要功能的手动检查。然而,现有的方法在训练之后拟合决策树,或者使用与新的学习技术(诸如使用神经网络的那些学习技术)不兼容的定制学习过程。为了解决这个问题,我们提出了一种新的马尔可夫决策过程(MDP)类型的学习决策树政策:迭代边界MDP(IBMDP)。IBMDP是围绕基本MDP构建的,因此在使用与方法无关的掩码过程时,保证每个IBMDP策略对应于基本MDP的决策树策略。由于这种决策树等价性,在训练期间可以使用任何函数近似器,包括神经网络,同时产生用于基本MDP的决策树策略。我们提出了所需的掩蔽过程,以及修改后的值更新步骤,允许IBMDP使用现有的算法来解决。我们应用这个过程来产生最近的强化学习方法的IBMDP变体。我们的经验表明,我们的方法的好处,通过解决IBMDP产生决策树政策的基础MDP。

英文摘要:

Current work in explainable reinforcement learning generally produces policies in the form of a decision tree over the state space. Such policies can be used for formal safety verification, agent behavior prediction, and manual inspection of important features. However, existing approaches fit a decision tree after training or use a custom learning procedure which is not compatible with new learning techniques, such as those which use neural networks. To address this limitation, we propose a novel Markov Decision Process (MDP) type for learning decision tree policies: Iterative Bounding MDPs (IBMDPs). An IBMDP is constructed around a base MDP so each IBMDP policy is guaranteed to correspond to a decision tree policy for the base MDP when using a method-agnostic masking procedure. Because of this decision tree equivalence, any function approximator can be used during training, including a neural network, while yielding a decision tree policy for the base MDP. We present the required masking procedure as well as a modified value update step which allows IBMDPs to be solved using existing algorithms. We apply this procedure to produce IBMDP variants of recent reinforcement learning methods. We empirically show the benefits of our approach by solving IBMDPs to produce decision tree policies for the base MDPs.

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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