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arXiv math/0112146math.COmath.PR
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关于0/1-多面体图的扩张

On the Expansion of Graphs of 0/1-Polytopes

Volker Kaibel

摘要:

图的边扩张是指图的一个割中的边数与被该割分开的两个节点集中较小的一个的大小之商的最小值。从下面界定边扩展对于从上面界定图上随机游动的“混合时间”是重要的。Mihail和Vazirani证明了0/1-多面体的图至少有一个边扩张。这个猜想的证明(甚至是一个较弱的猜想)将意味着随机近似计数理论中几个长期存在的开放问题的解决方案。我们提出了不同的技术,从下面的0/1-多面体的边缘扩展的边界。通过这些工具,我们表明,几类0/1-多面体确实有图的边扩张至少有一个。这些类包括维数最多为5的所有0/1-多面体、所有单0/1-多面体、所有超单形、所有独立集多面体和所有(完美)匹配多面体。

英文摘要:

The edge expansion of a graph is the minimum quotient of the number of edges in a cut and the size of the smaller one among the two node sets separated by the cut. Bounding the edge expansion from below is important for bounding the ``mixing time'' of a random walk on the graph from above. It has been conjectured by Mihail and Vazirani that the graph of every 0/1-polytope has edge expansion at least one. A proof of this (or even a weaker) conjecture would imply solutions of several long-standing open problems in the theory of randomized approximate counting. We present different techniques for bounding the edge expansion of a 0/1-polytope from below. By means of these tools we show that several classes of 0/1-polytopes indeed have graphs with edge expansion at least one. These classes include all 0/1-polytopes of dimension at most five, all simple 0/1-polytopes, all hypersimplices, all stable set polytopes, and all (perfect) matching polytopes.

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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