Pruning for efficient deterministic global optimization over trained ReLU neural networks

Fuente: arXiv
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Autores principales: Lastrucci, Giacomo, Karia, Tanuj, Schulte, Victor, Bongartz, Dominik, Schweidtmann, Artur M.
Formato: Preprint
Publicado: 2026
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author Lastrucci, Giacomo
Karia, Tanuj
Schulte, Victor
Bongartz, Dominik
Schweidtmann, Artur M.
author_facet Lastrucci, Giacomo
Karia, Tanuj
Schulte, Victor
Bongartz, Dominik
Schweidtmann, Artur M.
contents Neural networks are increasingly used as surrogates in optimization problems to replace computationally expensive models. However, embedding ReLU neural networks in mathematical programs introduces significant computational challenges, particularly for deep and wide networks, due to both the formulation of the ReLU disjunction and the resulting large-scale optimization problem. This work investigates how pruning techniques can accelerate the solution of optimization problems with embedded neural networks, focusing on the mechanisms underlying the computational gains. We provide theoretical insights into how both unstructured (weight) and structured (node) pruning affect the ReLU big-M formulation, showing that pruning monotonically tightens preactivation bounds. We conduct comprehensive empirical studies across multiple network architectures using an illustrative test function and a realistic chemical process flowsheet optimization case study. Our results show that pruning achieves speedups of up to three to four orders of magnitude, with computational gains attributed to three key factors: (i) reduction in problem size, (ii) decrease in the number of integer variables, and (iii) tightening of big-M bounds. Weight pruning is particularly effective for deep, narrow networks, while node pruning performs better for shallow, wide or medium-sized networks. In the chemical engineering case study, pruning enabled convergence within seconds for problems that were otherwise intractable. We recommend adopting pruning as standard practice when developing neural network surrogates for optimization, especially for engineering applications requiring repeated optimization solves.
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id arxiv_https___arxiv_org_abs_2603_23299
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pruning for efficient deterministic global optimization over trained ReLU neural networks
Lastrucci, Giacomo
Karia, Tanuj
Schulte, Victor
Bongartz, Dominik
Schweidtmann, Artur M.
Optimization and Control
Neural networks are increasingly used as surrogates in optimization problems to replace computationally expensive models. However, embedding ReLU neural networks in mathematical programs introduces significant computational challenges, particularly for deep and wide networks, due to both the formulation of the ReLU disjunction and the resulting large-scale optimization problem. This work investigates how pruning techniques can accelerate the solution of optimization problems with embedded neural networks, focusing on the mechanisms underlying the computational gains. We provide theoretical insights into how both unstructured (weight) and structured (node) pruning affect the ReLU big-M formulation, showing that pruning monotonically tightens preactivation bounds. We conduct comprehensive empirical studies across multiple network architectures using an illustrative test function and a realistic chemical process flowsheet optimization case study. Our results show that pruning achieves speedups of up to three to four orders of magnitude, with computational gains attributed to three key factors: (i) reduction in problem size, (ii) decrease in the number of integer variables, and (iii) tightening of big-M bounds. Weight pruning is particularly effective for deep, narrow networks, while node pruning performs better for shallow, wide or medium-sized networks. In the chemical engineering case study, pruning enabled convergence within seconds for problems that were otherwise intractable. We recommend adopting pruning as standard practice when developing neural network surrogates for optimization, especially for engineering applications requiring repeated optimization solves.
title Pruning for efficient deterministic global optimization over trained ReLU neural networks
topic Optimization and Control
url https://arxiv.org/abs/2603.23299