🤖 AI Summary
This study addresses the opacity of command-action mappings in Pareto-conditioned networks by proposing CF-ZOO, a novel method that formulates explanation generation as reward command intervention. By integrating boundary-guided directional search with zeroth-order optimization, CF-ZOO produces counterfactual explanations that elucidate underlying policy decision logic. This approach not only facilitates intuitive analysis of multi-objective reinforcement learning behaviors but also provides users with interpretable and actionable recommendations for preference adjustment. Consequently, the proposed framework significantly enhances both model interpretability and human-AI interactability, establishing a new paradigm for debugging and optimizing complex policies in conditional multi-objective settings.
📝 Abstract
Pareto Conditioned Networks learn multiple multi-objective reinforcement learning behaviours by conditioning a single policy on a desired return command. However, the local mapping from command and state to action remains opaque. We propose command-space counterfactual explanations for PCNs: given a fixed state, original command, and foil action, we search, in a black-box setting, for a minimally changed desired-return command under which the same trained policy would choose the foil. Our contributions are threefold. First, we formulate PCN explanations as return-command interventions, using a return-only PCN variant that avoids the added ambiguity of horizon-conditioning. Second, we adapt adversarial machine learning methods to reinforcement-learning explanations. Third, we introduce a boundary-seeded directional search that improves over purely local optimization in the command-action landscape, resulting in our proposed approach CF-ZOO. The resulting explanations are actionable and intuitively expressed in the user's own preferences: "If your trade-off had shifted slightly towards X, the agent would have chosen Y."