TL;DR
Reinforcement learning agents learn inefficiently because they don't exploit structural patterns in their environments. Reflex is a method that identifies and leverages reflection symmetry (mirror-image equivalences) in state-based continuous control tasks by integrating symmetry constraints into policy learning.
✦ Why It Matters
Engineers can reduce training time and computational cost by incorporating domain symmetries into RL algorithms for robotic control and continuous optimization tasks.
Key Takeaways
Full Summary
Reinforcement learning (RL)—where agents learn optimal behavior through trial and error—suffers from poor sample efficiency, requiring many environment interactions to learn effectively. Prior work exploited group-invariant MDPs (mathematical structures where certain transformations preserve problem structure), but focused on image-based RL and rotational symmetry, leaving state-based continuous control and reflection symmetry unexplored.
Reflex formalizes two reflection types—axial reflection (mirroring across a line) and bilateral reflection (left-right symmetry)—and integrates them into policy learning through symmetry regularization. The method works with both on-policy algorithms (PPO) and off-policy algorithms (SAC).
Experiments on OpenAI Gym and DeepMind Control Suite benchmarks demonstrated superior performance and improved sample efficiency compared to standard baselines, with code made publicly available.
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