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arXiv · 2505.21974

BOFormer: Learning to Solve Multi-Objective Bayesian Optimization via Non-Markovian RL

Yu-Heng Hung·Kai-Jie Lin·Yu-Heng Lin·Chien-Yi Wang·Cheng Sun·Ping-Chun Hsieh
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Abstract

Bayesian optimization (BO) offers an efficient pipeline for optimizing black-box functions with the help of a Gaussian process prior and an acquisition function (AF). Recently, in the context of single-objective BO, learning-based AFs witnessed promising empirical results given its favorable non-myopic nature. Despite this, the direct extension of these approaches to multi-objective Bayesian optimization (MOBO) suffer from the \textit{hypervolume identifiability issue}, which results from the non-Markovian nature of MOBO problems. To tackle this, inspired by the non-Markovian RL literature and the success of Transformers in language modeling, we present a generalized deep Q-learning framework and propose \textit{BOFormer}, which substantiates this framework for MOBO via sequence modeling. Through extensive evaluation, we demonstrate that BOFormer constantly outperforms the benchmark rule-based and learning-based algorithms in various synthetic MOBO and real-world multi-objective hyperparameter optimization problems. We have made the source code publicly available to encourage further research in this direction.

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Yu-Heng Hung, Kai-Jie Lin, Yu-Heng Lin, Chien-Yi Wang, Cheng Sun, Ping-Chun Hsieh. 2025-05-29. BOFormer: Learning to Solve Multi-Objective Bayesian Optimization via Non-Markovian RL. https://arxiv.org/abs/2505.21974

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