The symmetric vehicle routing problem with simultaneous pickup and deliveries is considered. The current state-of-the-art method to solve this problem employs the idea of a no-good cut. This article achieves an order of magnitude improvement in the computational time needed to solve difficult problem instances by generalizing the no-good cuts and developing a way to generate improved no-good cuts much earlier in a branch-and-bound tree. Results are reported on benchmark instances in literature and new difficult instances generated by the authors. Some polyhedral results are presented about the strength of the generalized no-good cuts for a special case of the problem.

中文翻译：

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具有同时取货和交货的对称车辆路径问题的新有效不等式

考虑同时提货和交货的对称车辆路径问题。解决这个问题的当前最先进的方法采用了无良切割的想法。本文通过推广不良切割并开发一种在分支定界树中更早生成改进的不良切割的方法，从而将解决困难问题实例所需的计算时间提高了一个数量级。结果报告在文献中的基准实例和作者产生的新的困难实例上。一些多面体结果是针对该问题的一个特殊情况给出了关于广义无良切割强度的一些结果。