arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.12245math.OCcs.DScs.NAmath.NA
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角约束最小生成树问题的改进公式和分枝切割算法

Improved Formulations and Branch-and-cut Algorithms for the Angular Constrained Minimum Spanning Tree Problem

Alexandre Salles da Cunha

摘要:

用完全无向图$G=(V,E)$和角度$α\in (0,2π]$定义了角度约束最小生成树问题($α$-MSTP). $G$的顶点定义了欧几里得平面中的点,而边,连接它们的线段,则由端点之间的欧几里得距离加权。如果对于任何$i \in V$,包围对应于其$i$ -入射边的所有线段的最小角度不超过$α$,则生成树是$G$的$α$ -生成树($α$ -ST)。$α$ -MSTP包括找到具有最小权重的$α$ -ST。我们介绍了两个$α-$ MSTP整数规划公式,${\mathcal F}_{xy}^*$和$\mathcal{F}_x^{++}$和他们的伴随分支和切割(BC)算法,BCFXY $^*$和BCFX $^{++}$。这两种配方都可以被看作是对来自文献的配方的改进。它们中最强的$\mathcal{F}_x^{++}$是通过以下方式获得的:(i)提升负责实施$α$角度约束的现有不等式集合,以及(ii)从我们在此公开的稳定集多面体($α-$ ST背后的结构)表征$α$-MSTP有效不等式。这些配方和他们的前辈在文献中进行了比较,从多面体的角度来看。从数值的角度来看,我们观察到BCFXY $^*$和BCFX $^{++}$优于文献中的竞争对手。事实上,由于$\mathcal{F}_x^{++}$提供的边界质量,BCFX $^{++}$似乎优于其他现有的$α-$ MSTP算法。它能够解决更多的情况下证明最优性,并提供更清晰的下限,当最优性没有证明在一个强加的时间限制。作为一个副产品,BCFX $^{++}$提供了8个新的最优性证书的实例来自文献。

英文摘要:

The Angular Constrained Minimum Spanning Tree Problem ($α$-MSTP) is defined in terms of a complete undirected graph $G=(V,E)$ and an angle $α\in (0,2π]$. Vertices of $G$ define points in the Euclidean plane while edges, the line segments connecting them, are weighted by the Euclidean distance between their endpoints. A spanning tree is an $α$-spanning tree ($α$-ST) of $G$ if, for any $i \in V$, the smallest angle that encloses all line segments corresponding to its $i$-incident edges does not exceed $α$. $α$-MSTP consists in finding an $α$-ST with the least weight. We introduce two $α-$MSTP integer programming formulations, ${\mathcal F}_{xy}^*$ and $\mathcal{F}_x^{++}$ and their accompanying Branch-and-cut (BC) algorithms, BCFXY$^*$ and BCFX$^{++}$. Both formulations can be seen as improvements over formulations coming from the literature. The strongest of them, $\mathcal{F}_x^{++}$, was obtained by: (i) lifting an existing set of inequalities in charge of enforcing $α$ angular constraints and (ii) characterizing $α$-MSTP valid inequalities from the Stable Set polytope, a structure behind $α-$STs, that we disclosed here. These formulations and their predecessors in the literature were compared from a polyhedral perspective. From a numerical standpoint, we observed that BCFXY$^*$ and BCFX$^{++}$ compare favorably to their competitors in the literature. In fact, thanks to the quality of the bounds provided by $\mathcal{F}_x^{++}$, BCFX$^{++}$ seems to outperform the other existing $α-$MSTP algorithms. It is able to solve more instances to proven optimality and to provide sharper lower bounds, when optimality is not attested within an imposed time limit. As a by-product, BCFX$^{++}$ provided 8 new optimality certificates for instances coming from the literature.

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。

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