Informed Asymmetric Actor-Critic: Theoretical Insights and Open Questions

Reinforcement learning in partially observable environments requires agents to make decisions under uncertainty, based on incomplete and noisy observations. Asymmetric actor-critic methods improve learning in these settings by exploiting privileged information available during training. Most existing approaches, however, assume full access to the true state. In this work, we present a novel asymmetric actor-critic formulation grounded in informed partially observable Markov decision processes, allowing the critic to leverage arbitrary privileged information without requiring full-state access. We show that the method preserves the policy gradient theorem and yields unbiased gradient estimates even when the critic conditions on privileged partial information. Furthermore, we provide a theoretical analysis of the informed asymmetric recurrent natural policy gradient algorithm derived from our informed asymmetric learning paradigm. Our findings challenge the assumption that full-state access is necessary for unbiased policy learning, motivating the need to develop well-defined criteria to quantify the informativeness of additional training signals and opening new directions for asymmetric reinforcement learning.

In Eighteenth European Workshop on Reinforcement Learning (EWRL 2025)