In safe Reinforcement Learning (RL), safety cost is typically defined as a function dependent on the immediate state and actions. In practice, safety constraints can often be non-Markovian due to the insufficient fidelity of state representation, and safety cost may not be known. We therefore address a general setting where safety labels (e.g., safe or unsafe) are associated with state-action trajectories. Our key contributions are: first, we design a safety model that specifically performs credit assignment to assess contributions of partial state-action trajectories on safety. This safety model is trained using a labeled safety dataset. Second, using RL-as-inference strategy we derive an effective algorithm for optimizing a safe policy using the learned safety model. Finally, we devise a method to dynamically adapt the tradeoff coefficient between reward maximization and safety compliance. We rewrite the constrained optimization problem into its dual problem and derive a gradient-based method to dynamically adjust the tradeoff coefficient during training. Our empirical results demonstrate that this approach is highly scalable and able to satisfy sophisticated non-Markovian safety constraints.

在安全强化学习中，我们设计了一个安全模型来评估部分状态-动作轨迹对安全性的贡献，并使用RL-as-inference策略推导出了一种有效的优化安全策略的算法，最后，我们提出了一种动态调整奖励最大化与安全合规性权衡系数的方法，实证结果表明这种方法规模可扩展且能满足复杂的非Markov安全约束。

学习的非马尔可夫安全性约束下的安全强化学习