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arXiv 1504.07019cs.DS
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路可分图的度量分解

Metric Decompositions of Path-Separable Graphs

Lior Kamma, Robert Krauthgamer

摘要:

在许多涉及度量空间的问题中,一个重要的工具是随机低直径分解的概念。不严格地说,$β$分解是指将度量划分为低直径集合的概率分布,使得附近的点(由$β>0$参数化)可能被“聚类”在一起。将此概念应用于边加权图中的最短路径度量,已知$n$ -顶点图允许$O(\ln n)$ -填充分解(Bartal,1996),并且排除子图允许$O(1)$ -填充分解(Klein,Plotkin and Rao 1993,Fakcharoenphol and Talwar 2003,Abraham et al. 2014)。我们设计了$p$ -路可分图族的分解,这是由Abraham和Gavoille(2006)定义的。并且指的是允许顶点分隔符在图中至多由$p$最短路径组成的图。我们的主要结果是:每个$p$ -路可分的$n$ -顶点图都有一个$O(\ln (p \ln n))$ -分解,它改进了一般图的$O(\ln n)$界,并为有界树宽图等图族提供了新的界.从技术上讲,我们的聚类过程与以前的不同之处在于,我们在精心选择的子图(的最短路径度量)中工作。

英文摘要:

A prominent tool in many problems involving metric spaces is a notion of randomized low-diameter decomposition. Loosely speaking, $β$-decomposition refers to a probability distribution over partitions of the metric into sets of low diameter, such that nearby points (parameterized by $β>0$) are likely to be "clustered" together. Applying this notion to the shortest-path metric in edge-weighted graphs, it is known that $n$-vertex graphs admit an $O(\ln n)$-padded decomposition (Bartal, 1996), and that excluded-minor graphs admit $O(1)$-padded decomposition (Klein, Plotkin and Rao 1993, Fakcharoenphol and Talwar 2003, Abraham et al. 2014). We design decompositions to the family of $p$-path-separable graphs, which was defined by Abraham and Gavoille (2006). and refers to graphs that admit vertex-separators consisting of at most $p$ shortest paths in the graph. Our main result is that every $p$-path-separable $n$-vertex graph admits an $O(\ln (p \ln n))$-decomposition, which refines the $O(\ln n)$ bound for general graphs, and provides new bounds for families like bounded-treewidth graphs. Technically, our clustering process differs from previous ones by working in (the shortest-path metric of) carefully chosen subgraphs.

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