🤖 AI Summary
Reinforcement learning (RL) faces the “curse of dimensionality” in high-dimensional tasks, while conventional curriculum learning relies on the unrealistic assumption that source and target tasks share an invariant optimal policy. Method: This paper introduces “causal alignment” from a causal inference perspective to ensure transferability of optimal decision rules between source and target tasks. Based on causal graph models, we derive the first sufficient condition for causal alignment. Our framework integrates causal modeling, counterfactual reasoning, and an adaptive curriculum generation algorithm, supporting both discrete and continuous action spaces as well as pixel-level observations. Results: Experiments demonstrate that our approach significantly improves policy transfer efficiency and final performance under unobserved confounding—outperforming standard curriculum learning in robustness and convergence speed.
📝 Abstract
A pervasive challenge in Reinforcement Learning (RL) is the"curse of dimensionality"which is the exponential growth in the state-action space when optimizing a high-dimensional target task. The framework of curriculum learning trains the agent in a curriculum composed of a sequence of related and more manageable source tasks. The expectation is that when some optimal decision rules are shared across source tasks and the target task, the agent could more quickly pick up the necessary skills to behave optimally in the environment, thus accelerating the learning process. However, this critical assumption of invariant optimal decision rules does not necessarily hold in many practical applications, specifically when the underlying environment contains unobserved confounders. This paper studies the problem of curriculum RL through causal lenses. We derive a sufficient graphical condition characterizing causally aligned source tasks, i.e., the invariance of optimal decision rules holds. We further develop an efficient algorithm to generate a causally aligned curriculum, provided with qualitative causal knowledge of the target task. Finally, we validate our proposed methodology through experiments in discrete and continuous confounded tasks with pixel observations.