Learning Loss Landscapes in Preference Optimization

Carlo Alfano, Silvia Sapora, Jakob Nicolaus Foerster, Patrick Rebeschini, Yee Whye Teh

Keywords: Preference optimization, mirror descent

Abstract:

We present a framework to discover preference optimization algorithms specialized to particular scenarios, in a theoretically sound and computationally efficient setting. We start by designing a novel family of PO algorithms based on mirror descent, which we call Mirror Preference Optimization (MPO). MPO recovers existing methods like Direct Preference Optimization (DPO) and Odds-Ratio Preference Optimization (ORPO) for specific choices of the mirror map. Given specific properties of preference datasets, such as mixed-quality or noisy data, we show that we can efficiently search the MPO class to find specialized algorithms that outperform current baselines. Namely, we leverage evolutionary strategies and preference datasets generated on MuJoCo environments to systematically evaluate and optimize MPO algorithms on hand-crafted scenarios. We demonstrate the resulting PO algorithms successfully transfer to a Large Language Model (LLM) alignment task, where they demonstrate superior robustness in handling mixed-quality datasets.

Primary Area: reinforcement learning

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Submission Number: 2402