AdamO: A Collapse-Suppressed Optimizer for Offline RL

TL;DR

AdamO is a novel optimizer designed to stabilize offline RL training by suppressing collapse through orthogonality constraints, improving stability and performance across benchmarks.

Contribution

This work introduces AdamO, an Adam-based optimizer with orthogonality correction, providing theoretical stability guarantees and empirical improvements in offline RL.

Findings

AdamO improves stability in offline RL training.

AdamO enhances returns across various benchmarks.

Orthogonality constraints prevent TD error amplification.

Abstract

Offline reinforcement learning (RL) can fail spectacularly when bootstrapped temporal-difference (TD) updates amplify their own errors, driving the critic toward extreme and unusable Q-values. A key counterintuitive insight of this work is that collapse is not only a property of the backup rule or network architecture: optimizer dynamics themselves can directly trigger or suppress instability. From a control-theoretic viewpoint, we model offline TD learning as a feedback system and analyze Adam-based critic updates. This yields a necessary and sufficient condition for stability of the induced local update dynamics: within the regime we analyze, these dynamics are stable if and only if the spectral radius of the corresponding update operator is strictly below one. Further analysis suggests that standard Adam updates can inadvertently distort the parameter geometry, motivating explicit orthogonality constraints to prevent TD error amplification. To this end, we propose AdamO, an Adam-based optimizer with a decoupled orthogonality correction regulated by a strict task-alignment budget. We prove that this design theoretically guarantees worst-case task safety and preserves Adam's continuous-time dissipative dynamics. Empirically, AdamO is broadly compatible with diverse offline RL baselines, improving stability and returns across a broad suite of benchmarks.