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A Spanner for the Day After
Discrete & Computational Geometry ( IF 0.6 ) Pub Date : 2020-08-06 , DOI: 10.1007/s00454-020-00228-6
Kevin Buchin , Sariel Har-Peled , Dániel Oláh

We show how to construct a \((1+\varepsilon )\)-spanner over a set \({P}\) of n points in \({\mathbb {R}}^d\) that is resilient to a catastrophic failure of nodes. Specifically, for prescribed parameters \({\vartheta },\varepsilon \in (0,1)\), the computed spanner \({G}\) has

$$\begin{aligned} {{\mathcal {O}}}\bigl (\varepsilon ^{-O(d)} {\vartheta }^{-6} n(\log \log n)^6 \log n \bigr ) \end{aligned}$$

edges. Furthermore, for anyk, and any deleted set \({{B}}\subseteq {P}\) of k points, the residual graph \({G}\setminus {{B}}\) is a \((1+\varepsilon )\)-spanner for all the points of \({P}\) except for \((1+{\vartheta })k\) of them. No previous constructions, beyond the trivial clique with \({{\mathcal {O}}}(n^2)\) edges, were known with this resilience property (i.e., only a tiny additional fraction of vertices, \(\vartheta |B|\), lose their distance preserving connectivity). Our construction works by first solving the exact problem in one dimension, and then showing a surprisingly simple and elegant construction in higher dimensions, that uses the one-dimensional construction in a black-box fashion.



中文翻译:

第二天的扳手

我们展示了如何在\({\ mathbb {R}} ^ d \)中具有n个点的一组\({P} \)上构造一个\((1+ \ varepsilon)\)-扳手,该扳手对节点的灾难性故障。具体来说,对于指定参数\({\ vartheta},\ varepsilon \ in(0,1)\),计算出的扳手\({G} \)具有

$$ \ begin {aligned} {{\ mathcal {O}}} \ bigl(\ varepsilon ^ {-O(d)} {\ vartheta} ^ {-6} n(\ log \ log n)^ 6 \ log n \ bigr)\ end {aligned} $$

边缘。此外,对于任何ķ,和任何删除集\({{B}} \ subseteq {P} \)ķ分,剩余图\({G} \ setminus {{B}} \)是一个\(( 1+ \ varepsilon)\) -spanner对于所有的点\({P} \)除了\((1 + {\ vartheta})K \)它们。除了具有\({{\ mathcal {O}}}(n ^ 2)\)边的琐碎小集团之外,没有其他构造具有此弹性属性(即,顶点的一小部分只是\(\ vartheta) | B | \),失去了保持连接的距离)。我们的构造首先通过在一个维度上解决确切的问题,然后在更高维度上显示出令人惊讶的简单而优雅的构造来工作,该构造以黑盒子的方式使用一维构造。

更新日期:2020-08-06
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