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A black-box optimization method with polynomial-based kernels and quadratic-optimization annealing

Yuki Minamoto, Yuya Sakamoto

TL;DR

Kernel-QA presents a black-box optimization approach that builds analytic surrogates using a second-order polynomial kernel within a QUBO framework, enabling efficient use of Ising machines. By employing a representer-theorem-based surrogate, Woodbury updates, a priori domain-wall encoding for variable conversion, and an exponential transformation of outputs, the method targets high-dimensional, multi-modal landscapes while avoiding overfitting. Across Rosenbrock and Rastrigin benchmarks in real and binary variables up to $d=80$ and $d_B=640$, kernel-QA demonstrates strong final performance and reduced sensitivity to dimensionality compared with Bayesian optimization, with occasional gains from a carefully tuned exploration term. The work highlights a robust, scalable BBO path that leverages Ising-machine optimization, offering practical impact for expensive black-box problems with large decision spaces.

Abstract

We introduce kernel-QA, a black-box optimization (BBO) method that constructs surrogate models analytically using low-order polynomial kernels within a quadratic unconstrained binary optimization (QUBO) framework, enabling efficient utilization of Ising machines. The method has been evaluated on artificial landscapes, ranging from uni-modal to multi-modal, with input dimensions extending to 80 for real variables and 640 for binary variables. The results demonstrate that kernel-QA is particularly effective for optimizing black-box functions characterized by local minima and high-dimensional inputs, showcasing its potential as a robust and scalable BBO approach.

A black-box optimization method with polynomial-based kernels and quadratic-optimization annealing

TL;DR

Kernel-QA presents a black-box optimization approach that builds analytic surrogates using a second-order polynomial kernel within a QUBO framework, enabling efficient use of Ising machines. By employing a representer-theorem-based surrogate, Woodbury updates, a priori domain-wall encoding for variable conversion, and an exponential transformation of outputs, the method targets high-dimensional, multi-modal landscapes while avoiding overfitting. Across Rosenbrock and Rastrigin benchmarks in real and binary variables up to and , kernel-QA demonstrates strong final performance and reduced sensitivity to dimensionality compared with Bayesian optimization, with occasional gains from a carefully tuned exploration term. The work highlights a robust, scalable BBO path that leverages Ising-machine optimization, offering practical impact for expensive black-box problems with large decision spaces.

Abstract

We introduce kernel-QA, a black-box optimization (BBO) method that constructs surrogate models analytically using low-order polynomial kernels within a quadratic unconstrained binary optimization (QUBO) framework, enabling efficient utilization of Ising machines. The method has been evaluated on artificial landscapes, ranging from uni-modal to multi-modal, with input dimensions extending to 80 for real variables and 640 for binary variables. The results demonstrate that kernel-QA is particularly effective for optimizing black-box functions characterized by local minima and high-dimensional inputs, showcasing its potential as a robust and scalable BBO approach.
Paper Structure (20 sections, 18 equations, 11 figures, 1 table)

This paper contains 20 sections, 18 equations, 11 figures, 1 table.

Figures (11)

  • Figure 1: A flow of a typical serial optimization for a black-box objective function.
  • Figure 2: The two-dimensional ($d=2$) landscapes of the test functions, (a) Rosenbrock and (b) Rastrigin functions, in logarithm scale.
  • Figure 3: Evolution of $f(\mathbf{x}_{best, i})$ for (a) Rosenbrock and (b) Rastrigin functions with the real-variable dimension $d=5$ (r5h). Optimization uses kernel-QA (red) and Bayesian optimization (black). Corresponding results of FMQA are also shown in blue as a reference. Note that plots in the negative cycles evaluate $f(\mathbf{x})$ for the initial training dataset.
  • Figure 4: Evolution of the distance between the found and true solutions obtained for Fig. \ref{['fig:rastrigin_kq_bo_fm_d5']}.
  • Figure 5: Evolution of $f(\mathbf{x}_{best, i})$ with various real-variable dimensions $d=5$ (thin solid), $10$ (dashed), $20$ (dotted), $40$ (dash-dotted) and $80$ (solid line), for (a) Rosenbrock and (b) Rastrigin functions. Optimization uses kernel-QA (red) and Bayesian optimization (black). Note that plots in the negative cycles evaluate $f(\mathbf{x})$ for the initial training dataset.
  • ...and 6 more figures