Quantifying uncertainty with ensembles of surrogates for blackbox optimization

TL;DR

This paper introduces uncertainty measures for ensembles of surrogates in blackbox optimization, enhancing Bayesian optimization and improving exploration in mesh adaptive direct search, leading to more efficient solutions for expensive problems.

Contribution

It proposes novel uncertainty measures for surrogate ensembles and integrates them into MADS, advancing exploration capabilities in blackbox optimization.

Findings

Outperforms stochastic models in accuracy and efficiency

Enhances exploration in mesh adaptive direct search

Effective on diverse analytical and simulation problems

Abstract

This work is in the context of blackbox optimization where the functions defining the problem are expensive to evaluate and where no derivatives are available. A tried and tested technique is to build surrogates of the objective and the constraints in order to conduct the optimization at a cheaper computational cost. This work proposes different uncertainty measures when using ensembles of surrogates. The resulting combination of an ensemble of surrogates with our measures behaves as a stochastic model and allows the use of efficient Bayesian optimization tools. The method is incorporated in the search step of the mesh adaptive direct search (MADS) algorithm to improve the exploration of the search space. Computational experiments are conducted on seven analytical problems, two multi-disciplinary optimization problems and two simulation problems. The results show that the proposed approach solves expensive simulation-based problems at a greater precision and with a lower computational effort than stochastic models.