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arXiv 1104.5214cs.DScs.DM
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平面图、有界亏格图和无子图的线性空间近似距离预言

Linear-Space Approximate Distance Oracles for Planar, Bounded-Genus, and Minor-Free Graphs

Ken-ichi Kawarabayashi, Philip N. Klein, Christian Sommer

摘要:

图的(1 + eps)-近似距离预言机是支持近似点到点最短路径距离查询的数据结构。距离预言机构造的最相关的度量是:空间、查询时间和预处理时间。平面图(Thorup,JACM'04)和随后的小排除图(Abraham和Gavoille,PODC'06)都有强距离预言结构。然而,对于n节点图,这些需要Omega(eps^{-1} n lg n)空间。我们认为,一个非常低的空间要求是必不可少的。由于现代计算机体系结构涉及分级存储器(高速缓存、主存储器、辅助存储器),因此高存储器需求实际上可能大大增加实际运行时间。此外,我们希望数据结构可以部署在小型移动设备上,例如手持设备,其具有相对较小的主存储器。在本文中,对于平面图,有界亏格图,和小排除图,我们给出的距离预言的结构,只需要O(n)空间。大O只隐藏一个固定常数,与ε无关,也与亏格或被排除子式的大小无关。我们的距离预言机的预处理时间也比以前已知的构造更快。对于平面图,预处理时间为O(nlg^2n)。然而,我们的构造具有较慢的查询时间。对于平面图,查询时间为O(eps^{-2} lg^2 n)。对于我们的线性空间结果,我们实际上可以确保,对于任何delta > 0,所需的空间仅为表示图本身所需空间的1 + delta倍。

英文摘要:

A (1 + eps)-approximate distance oracle for a graph is a data structure that supports approximate point-to-point shortest-path-distance queries. The most relevant measures for a distance-oracle construction are: space, query time, and preprocessing time. There are strong distance-oracle constructions known for planar graphs (Thorup, JACM'04) and, subsequently, minor-excluded graphs (Abraham and Gavoille, PODC'06). However, these require Omega(eps^{-1} n lg n) space for n-node graphs. We argue that a very low space requirement is essential. Since modern computer architectures involve hierarchical memory (caches, primary memory, secondary memory), a high memory requirement in effect may greatly increase the actual running time. Moreover, we would like data structures that can be deployed on small mobile devices, such as handhelds, which have relatively small primary memory. In this paper, for planar graphs, bounded-genus graphs, and minor-excluded graphs we give distance-oracle constructions that require only O(n) space. The big O hides only a fixed constant, independent of εand independent of genus or size of an excluded minor. The preprocessing times for our distance oracle are also faster than those for the previously known constructions. For planar graphs, the preprocessing time is O(n lg^2 n). However, our constructions have slower query times. For planar graphs, the query time is O(eps^{-2} lg^2 n). For our linear-space results, we can in fact ensure, for any delta > 0, that the space required is only 1 + delta times the space required just to represent the graph itself.

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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