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Optimizing the Unknown: Black Box Bayesian Optimization with Energy-Based Model and Reinforcement Learning

Ruiyao Miao, Junren Xiao, Shiya Tsang, Hui Xiong, Yingnian Wu

TL;DR

The Reinforced Energy-Based Model for Bayesian Optimization (REBMBO) is proposed, which integrates Gaussian Processes for local guidance with an Energy-Based Model (EBM) to capture global structural information and dynamically adjusts the depth and direction of exploration to effectively overcome the limitations of traditional BO methods.

Abstract

Existing Bayesian Optimization (BO) methods typically balance exploration and exploitation to optimize costly objective functions. However, these methods often suffer from a significant one-step bias, which may lead to convergence towards local optima and poor performance in complex or high-dimensional tasks. Recently, Black-Box Optimization (BBO) has achieved success across various scientific and engineering domains, particularly when function evaluations are costly and gradients are unavailable. Motivated by this, we propose the Reinforced Energy-Based Model for Bayesian Optimization (REBMBO), which integrates Gaussian Processes (GP) for local guidance with an Energy-Based Model (EBM) to capture global structural information. Notably, we define each Bayesian Optimization iteration as a Markov Decision Process (MDP) and use Proximal Policy Optimization (PPO) for adaptive multi-step lookahead, dynamically adjusting the depth and direction of exploration to effectively overcome the limitations of traditional BO methods. We conduct extensive experiments on synthetic and real-world benchmarks, confirming the superior performance of REBMBO. Additional analyses across various GP configurations further highlight its adaptability and robustness.

Optimizing the Unknown: Black Box Bayesian Optimization with Energy-Based Model and Reinforcement Learning

TL;DR

The Reinforced Energy-Based Model for Bayesian Optimization (REBMBO) is proposed, which integrates Gaussian Processes for local guidance with an Energy-Based Model (EBM) to capture global structural information and dynamically adjusts the depth and direction of exploration to effectively overcome the limitations of traditional BO methods.

Abstract

Existing Bayesian Optimization (BO) methods typically balance exploration and exploitation to optimize costly objective functions. However, these methods often suffer from a significant one-step bias, which may lead to convergence towards local optima and poor performance in complex or high-dimensional tasks. Recently, Black-Box Optimization (BBO) has achieved success across various scientific and engineering domains, particularly when function evaluations are costly and gradients are unavailable. Motivated by this, we propose the Reinforced Energy-Based Model for Bayesian Optimization (REBMBO), which integrates Gaussian Processes (GP) for local guidance with an Energy-Based Model (EBM) to capture global structural information. Notably, we define each Bayesian Optimization iteration as a Markov Decision Process (MDP) and use Proximal Policy Optimization (PPO) for adaptive multi-step lookahead, dynamically adjusting the depth and direction of exploration to effectively overcome the limitations of traditional BO methods. We conduct extensive experiments on synthetic and real-world benchmarks, confirming the superior performance of REBMBO. Additional analyses across various GP configurations further highlight its adaptability and robustness.
Paper Structure (122 sections, 11 theorems, 149 equations, 10 figures, 18 tables, 1 algorithm)

This paper contains 122 sections, 11 theorems, 149 equations, 10 figures, 18 tables, 1 algorithm.

Key Result

Proposition H.1

If the reward $r_t$ is uniformly bounded, i.e.$\lvert r_t\rvert \le R_{\max}$, and the value function estimator is sufficiently accurate, then under mild Lipschitz assumptions on $\nabla_\phi \log \pi_\phi(\mathbf{a}_t \mid \mathbf{s}_t)$, the PPO updates converge to a stable policy that locally max

Figures (10)

  • Figure 1: REBMBO Workflow Diagram. The architecture comprises: Module A for local modeling using GP posterior; Module B which trains an EBM to capture global structure; and Module C, which uses PPO-based RL agents to generate decisions and optimize via rewards shaped by both function values and EBM energy signals. Arrows of different colors represent distinct data flows: green arrows indicate model parameter updates, and purple arrows represent RL actions, evaluation or feedback steps.
  • Figure 2: Bayesian optimization performance across benchmarks: (a) Branin 2D, (b) Ackley 5D, (c) Rosenbrock 8D, (d) HDBO 200D, (e) Nanophotonic 3D, (f) Rosetta 86D. REBMBO variants (blue shades) consistently outperform baselines, especially in higher dimensions.
  • Figure 3: 1D multi-modal function experiment. The top panel shows the true function (dashed), GP mean (solid), and sampled points from UCB (purple) vs. EBM-UCB (orange). The middle panel illustrates the learned negative energy $-E_\theta(x)$. The bottom panel compares the two acquisition functions, emphasizing how EBM-UCB better targets the global peak near $x\approx0.25$.
  • Figure 4: 2D multi-modal decomposition of REBMBO. Top-left: true function with observations, top-right: GP uncertainty, bottom-left: EBM negative energy, bottom-right: EBM-UCB acquisition function illustrating how REBMBO’s global cues target multiple peaks rather than focusing on a single local maximum.
  • Figure 5: Trajectories of GP-UCB, GLASSES, and REBMBO on a 2D multi-modal function with two main peaks. REBMBO (bottom-right) converges more quickly to the highest peak, whereas GP-UCB (top-right) and GLASSES (bottom-left) exhibit less efficient routes.
  • ...and 5 more figures

Theorems & Definitions (21)

  • proof : Detailed derivation for CDF
  • proof : Probability of Duel Derivation
  • Proposition H.1: Bounded Rewards and PPO Convergence
  • Theorem I.1
  • Lemma I.2: Deviation Bound
  • proof
  • Lemma I.3: Bound on Instantaneous Regret
  • proof
  • Lemma I.4: Information Gain Expression
  • proof : Outline
  • ...and 11 more