arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.2397cs.DS
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增量循环检测、拓扑排序和强构件维护

Incremental Cycle Detection, Topological Ordering, and Strong Component Maintenance

Bernhard Haeupler, Telikepalli Kavitha, Rogers Mathew, Siddhartha Sen, Robert Endre Tarjan

摘要:

我们提出了两个在线算法,用于维护一个有向$n$ -顶点无环图的拓扑顺序作为弧添加,并检测一个循环时,创建。我们的第一个算法在$O(m^{3/2})$时间内处理$m$弧加法。对于稀疏图($m/n = O(1)$),该界通过对数因子改进了先前的最佳界,并且在满足自然{ \em局部性}属性的算法中,该界紧到常数因子内。我们的第二个算法在$O(n^{5/2})$时间内处理任意序列的弧加法。对于足够密集的图,这个界限提高了最好的前一个多项式因子的界限。我们的界限可能是远离紧密:我们表明,该算法可以采取$Ω(n^2 2^{\sqrt{2\lg n}})$的时间有关其性能的概括的$k$水平的组合几何问题。最近,Bender、Fineman和Gilbert给出了一个在$Θ(n^2 \log n)$时间内运行的完全不同的算法。我们扩展我们的算法,以维护强组件,而不影响渐近时间界。

英文摘要:

We present two on-line algorithms for maintaining a topological order of a directed $n$-vertex acyclic graph as arcs are added, and detecting a cycle when one is created. Our first algorithm handles $m$ arc additions in $O(m^{3/2})$ time. For sparse graphs ($m/n = O(1)$), this bound improves the best previous bound by a logarithmic factor, and is tight to within a constant factor among algorithms satisfying a natural {\em locality} property. Our second algorithm handles an arbitrary sequence of arc additions in $O(n^{5/2})$ time. For sufficiently dense graphs, this bound improves the best previous bound by a polynomial factor. Our bound may be far from tight: we show that the algorithm can take $Ω(n^2 2^{\sqrt{2\lg n}})$ time by relating its performance to a generalization of the $k$-levels problem of combinatorial geometry. A completely different algorithm running in $Θ(n^2 \log n)$ time was given recently by Bender, Fineman, and Gilbert. We extend both of our algorithms to the maintenance of strong components, without affecting the asymptotic time bounds.

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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