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arXiv 0909.4692cs.DScs.DM
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再论平面子图同构

Planar Subgraph Isomorphism Revisited

Frederic Dorn

摘要:

子图同构问题的定义如下:给定一个模式H和一个n个顶点的主图G,G是否包含一个与H同构的子图?Eppstein [SODA 95,J 'GAA 99]给出了第一个线性时间算法,用于固定大小模式的子图同构,比如阶数k和任意平面主图,改进了O(n^ \sqrt{k})-时间算法,当使用Alon等人[J' ACM 95]的“颜色编码”技术时。Eppstein算法的时间复杂度为k^O(k)n,也就是说,对k的依赖是超指数的。我们解决了Eppstein的论文中提出的一个公开问题,并将运行时间提高到2^O(k)n,即在k中保持单指数,而在n中保持项线性。在判定子图同构之后,我们可以构造一个解并在相同的渐近运行时间内枚举所有解。我们可以列出w个子图,在我们的算法的运行时间O(w k)的加法项。我们介绍了“嵌入式动态规划“的技术,适当结构化的图分解,它利用的拓扑结构的底层嵌入的子图模式(而不是主机图)。为了实现我们的结果,我们给出了一个上限的部分解决方案的数量在每个动态规划步骤作为一个功能的模式大小-事实证明,平面子图同构问题,该功能是单指数的顶点数的模式。

英文摘要:

The problem of Subgraph Isomorphism is defined as follows: Given a pattern H and a host graph G on n vertices, does G contain a subgraph that is isomorphic to H? Eppstein [SODA 95, J'GAA 99] gives the first linear time algorithm for subgraph isomorphism for a fixed-size pattern, say of order k, and arbitrary planar host graph, improving upon the O(n^\sqrt{k})-time algorithm when using the ``Color-coding'' technique of Alon et al [J'ACM 95]. Eppstein's algorithm runs in time k^O(k) n, that is, the dependency on k is superexponential. We solve an open problem posed in Eppstein's paper and improve the running time to 2^O(k) n, that is, single exponential in k while keeping the term in n linear. Next to deciding subgraph isomorphism, we can construct a solution and enumerate all solutions in the same asymptotic running time. We may list w subgraphs with an additive term O(w k) in the running time of our algorithm. We introduce the technique of "embedded dynamic programming" on a suitably structured graph decomposition, which exploits the topology of the underlying embeddings of the subgraph pattern (rather than of the host graph). To achieve our results, we give an upper bound on the number of partial solutions in each dynamic programming step as a function of pattern size--as it turns out, for the planar subgraph isomorphism problem, that function is single exponential in the number of vertices in the pattern.

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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