On Normative Reinforcement Learning via Safe Reinforcement Learning

Reinforcement learning (RL) has proven a successful technique for teaching autonomous agents goal-directed behaviour. As RL agents further integrate with our society, they must learn to comply with ethical, social, or legal norms. Defeasible deontic logics are natural formal frameworks to specify and reason about such norms in a transparent way. However, their effective and efficient integration in RL agents remains an open problem. On the other hand, linear temporal logic (LTL) has been successfully employed to synthesize RL policies satisfying, e.g., safety requirements. In this paper, we investigate the extent to which the established machinery for safe reinforcement learning can be leveraged for directing normative behaviour for RL agents. We analyze some of the difficulties that arise from attempting to represent norms with LTL, provide an algorithm for synthesizing LTL specifications from certain normative systems, and analyze its power and limits with a case study.