Meta-learning objectives for preference optimization

Conference item

Evaluating preference optimization (PO) algorithms on LLM alignment is a challenging task that presents prohibitive costs, noise, and several variables like model size and hyper-parameters. In this work, we show that it is possible to gain insights on the efficacy of PO algorithm on much simpler benchmarks. We design a diagnostic suite of MuJoCo tasks and datasets, which we use to systematically evaluate PO algorithms, establishing a more controlled and cheaper benchmark. We then propose a novel family of PO algorithms based on mirror descent, which we call Mirror Preference Optimization (MPO). Through evolutionary strategies, we search this class to discover algorithms specialized to specific properties of preference datasets, such as mixed-quality or noisy data. We demonstrate that our discovered PO algorithms outperform all known algorithms in the targeted MuJoCo settings. Finally, based on the insights gained from our MuJoCo experiments, we design a novel PO algorithm that significantly outperforms existing baselines in an LLM alignment task.

Authors: Alfano, C; Sapora, S; Foester, JN; Rebeschini, P; Teh, YW

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: NeurIPS
• Article number: 115760
• Publication date: 2025-12-03
• Acceptance date: 2025-09-18
• Event title: 39th Conference on Neural Information Processing Systems (NeurIPS 2025)
• Event location: San Diego, CA, USA
• Event website: https://neurips.cc/Conferences/2025
• Event start date: 2025-12-02
• Event end date: 2025-12-07
• Language: English