LMask: Learn to Solve Constrained Routing Problems with Lazy Masking

Fuente: arXiv
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Auteurs principaux: Li, Tianyou, Zou, Haijun, Wu, Jiayuan, Wen, Zaiwen
Format: Preprint
Publié: 2025
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author Li, Tianyou
Zou, Haijun
Wu, Jiayuan
Wen, Zaiwen
author_facet Li, Tianyou
Zou, Haijun
Wu, Jiayuan
Wen, Zaiwen
contents Routing problems are canonical combinatorial optimization tasks with wide-ranging applications in logistics, transportation, and supply chain management. However, solving these problems becomes significantly more challenging when complex constraints are involved. In this paper, we propose LMask, a novel learning framework that utilizes dynamic masking to generate high-quality feasible solutions for constrained routing problems. LMask introduces the LazyMask decoding method, which lazily refines feasibility masks with the backtracking mechanism. In addition, it employs the refinement intensity embedding to encode the search trace into the model, mitigating representation ambiguities induced by backtracking. To further reduce sampling cost, LMask sets a backtracking budget during decoding, while constraint violations are penalized in the loss function during training to counteract infeasibility caused by this budget. We provide theoretical guarantees for the validity and probabilistic optimality of our approach. Extensive experiments on the traveling salesman problem with time windows (TSPTW) and TSP with draft limits (TSPDL) demonstrate that LMask achieves state-of-the-art feasibility rates and solution quality, outperforming existing neural methods.
format Preprint
id arxiv_https___arxiv_org_abs_2505_17938
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle LMask: Learn to Solve Constrained Routing Problems with Lazy Masking
Li, Tianyou
Zou, Haijun
Wu, Jiayuan
Wen, Zaiwen
Optimization and Control
Artificial Intelligence
Machine Learning
90C27, 68T20
Routing problems are canonical combinatorial optimization tasks with wide-ranging applications in logistics, transportation, and supply chain management. However, solving these problems becomes significantly more challenging when complex constraints are involved. In this paper, we propose LMask, a novel learning framework that utilizes dynamic masking to generate high-quality feasible solutions for constrained routing problems. LMask introduces the LazyMask decoding method, which lazily refines feasibility masks with the backtracking mechanism. In addition, it employs the refinement intensity embedding to encode the search trace into the model, mitigating representation ambiguities induced by backtracking. To further reduce sampling cost, LMask sets a backtracking budget during decoding, while constraint violations are penalized in the loss function during training to counteract infeasibility caused by this budget. We provide theoretical guarantees for the validity and probabilistic optimality of our approach. Extensive experiments on the traveling salesman problem with time windows (TSPTW) and TSP with draft limits (TSPDL) demonstrate that LMask achieves state-of-the-art feasibility rates and solution quality, outperforming existing neural methods.
title LMask: Learn to Solve Constrained Routing Problems with Lazy Masking
topic Optimization and Control
Artificial Intelligence
Machine Learning
90C27, 68T20
url https://arxiv.org/abs/2505.17938