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When two objectives conflict, training one policy per preference wastes data, so this routes between a small set instead

AspireAI community · arXiv
Multi-objective reinforcement learning has to balance competing objectives, such as helpfulness against honesty in safety work, or speed against energy in robotics, and the optimal policy can shift sharply with the objective weighting, which makes per-preference policy learning sample-inefficient. This paper introduces objective-conflict coefficients and derives near-optimal regret bounds for online settings using them, then designs routed ensemble policy learning, which keeps a small set of basis policies and dynamically routes trajectories to the one with the highest potential reward, plus a kernel surrogate trajectory attribution algorithm that estimates how feedback on one trajectory influences learning on others, capturing nonlinear synergy and antagonism. Routed ensembles improve average performance by 4.3% over baselines on Meta-World and MO-Gymnasium, attribution correlation with leave-one-out analysis improves by 50%, and applying attribution to trajectory selection yields 27% higher reward. An extended version appears at NeurIPS 2026.
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