arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2403.00262math.OC
收藏

一类用于车辆路径问题的新型紧凑建模

A New Class of Compact Formulations for Vehicle Routing Problems

Udayan Mandal, Amelia Regan, Louis Martin Rousseau, Julian Yarkony

AI总结:

针对VRPTW,本文提出新型紧凑MILP模型与离散化发现算法,通过迭代调节时间、容量和局部初等性约束,获得低复杂度且整数间隙更小的LP松弛。

摘要:

本文介绍了一种新颖的紧凑混合整数线性规划(MILP)模型,以及一种用于带时间窗车辆路径问题(VRPTW)的、基于离散化发现的求解方法。我们的目标是通过约束线性规划(LP)解,使其仅使用与时间和容量可行路径相对应的流,从而高效求解该优化问题;这些路径是局部初等的,即禁止出现客户在空间上局部集中的环。我们采用离散化发现算法来迭代改进LP松弛。该迭代过程在两个步骤之间交替:(1)增强对时间、容量和初等性的强制约束,以提高LP目标值,但代价是复杂性增加(更多变量和约束);(2)在不降低LP目标值的情况下减弱强制约束,以降低复杂性。这种迭代方法确保我们以最小的复杂性生成一个紧密逼近最优MILP目标值的LP松弛,从而便于通过现成的MILP求解器进行高效求解。我们通过在经典VRPTW实例上的实证评估证明了该方法的有效性。我们展示了求解最终MILP和多轮LP松弛的效率,并强调了最终LP松弛减小的整数间隙。我们相信,该方法在解决VRPTW领域内外的广泛路径问题方面具有前景。

英文摘要:

This paper introduces a novel compact mixed integer linear programming (MILP) formulation and a discretization discovery-based solution approach for the Vehicle Routing Problem with Time Windows (VRPTW). We aim to solve the optimization problem efficiently by constraining the linear programming (LP) solutions to use only flows corresponding to time and capacity-feasible routes that are locally elementary (prohibiting cycles of customers localized in space). We employ a discretization discovery algorithm to refine the LP relaxation iteratively. This iterative process alternates between two steps: (1) increasing time/capacity/elementarity enforcement to increase the LP objective, albeit at the expense of increased complexity (more variables and constraints), and (2) decreasing enforcement without decreasing the LP objective to reduce complexity. This iterative approach ensures we produce an LP relaxation that closely approximates the optimal MILP objective with minimal complexity, facilitating an efficient solution via an off-the-shelf MILP solver. The effectiveness of our method is demonstrated through empirical evaluations on classical VRPTW instances. We showcase the efficiency of solving the final MILP and multiple iterations of LP relaxations, highlighting the decreased integrality gap of the final LP relaxation. We believe that our approach holds promise for addressing a wide range of routing problems within and beyond the VRPTW domain.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑