Learning to delegate for large-scale vehicle routingDownload PDF

21 May 2021, 20:48 (edited 11 Jan 2022)NeurIPS 2021 SpotlightReaders: Everyone
  • Keywords: machine learning, combinatorial optimization, vehicle routing, decomposition
  • Abstract: Vehicle routing problems (VRPs) form a class of combinatorial problems with wide practical applications. While previous heuristic or learning-based works achieve decent solutions on small problem instances, their performance deteriorates in large problems. This article presents a novel learning-augmented local search framework to solve large-scale VRP. The method iteratively improves the solution by identifying appropriate subproblems and $delegating$ their improvement to a black box subsolver. At each step, we leverage spatial locality to consider only a linear number of subproblems, rather than exponential. We frame subproblem selection as regression and train a Transformer on a generated training set of problem instances. Our method accelerates state-of-the-art VRP solvers by 10x to 100x while achieving competitive solution qualities for VRPs with sizes ranging from 500 to 3000. Learned subproblem selection offers a 1.5x to 2x speedup over heuristic or random selection. Our results generalize to a variety of VRP distributions, variants, and solvers.
  • Supplementary Material: pdf
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  • Code: https://github.com/mit-wu-lab/learning-to-delegate
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