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arXiv 2410.06337cs.DS
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图单极性问题的更快算法

Faster Algorithms for Graph Monopolarity

Geevarghese Philip, Shrinidhi Teganahally Sridhara

AI总结:

本文针对图单极识别问题,利用到无椅子图的顶点调制器设计多项式时间子程序,进而提出 $\mathcal{O}^{\star}(1.3734^{n})$ 时间的精确算法以及参数为到无爪图调制器大小的 FPT 算法,首次突破平凡 $2^n$ 时间界限。

摘要:

一个图 $G = (V,E)$ 被称为单极图,如果其顶点集存在一个划分 $V = (C \uplus{} I)$,其中 $G[C]$ 是一个簇图,且 $I$ 是 $G$ 中的一个独立集;这样的划分称为 $G$ 的单极划分。单极识别问题——判断输入图是否为单极图——已知在非常受限的图类(如次立方平面图)中也是 NP 难的。我们推导出一个多项式时间算法,该算法以 (i) 一个图 $G=(V,E)$ 和 (ii) 一个将 $G$ 调制为无椅子图的顶点调制器 $S$ 作为输入,并检查 $G$ 是否存在一个单极划分 $V=(C\uplus{}I)$,使得集合 $S$ 包含在簇部分中。我们基于该算法开发了用于单极识别问题的快速精确指数时间算法和参数化算法。我们的精确算法在具有 $n$ 个顶点的输入图上以 $\mathcal{O}^{\star}(1.3734^{n})$ 时间解决单极识别问题,其中 $\mathcal{O}^{\star}()$ 记号隐藏多项式因子。事实上,我们以 $\mathcal{O}^{\star}(1.3734^{n})$ 时间解决了更一般的问题——单极扩展问题和列表单极划分问题。这是对所有这些问题平凡 $\mathcal{O}^{\star}(2^{n})$ 时间算法的首次改进。已知在指数时间假设(ETH)下,这些问题无法在 $\mathcal{O}^{\star}(2^{o(n)})$ 时间内解决。我们的 FPT 算法分别以 $\mathcal{O}^{\star}(3.076^{k_{v}})$ 和 $\mathcal{O}^{\star}(2.253^{k_{e}})$ 时间解决单极识别问题,其中 $k_{v}$ 和 $k_{e}$ 分别是输入图到无爪图的最小顶点调制器和边调制器的大小。这些结果是对目前已知的少量单极识别问题 FPT 算法的重要补充。

英文摘要:

A graph $G = (V,E)$ is $\textit{monopolar}$ if its vertex set admits a partition $V = (C \uplus{} I)$ where $G[C]$ is a $\textit{cluster graph}$ and $I$ is an $\textit{independent set}$ in $G$; this is a \textit{monopolar partition} of $G$. The MONOPOLAR RECOGNITION problem -- deciding whether an input graph is monopolar -- is known to be NP-Hard in very restricted graph classes such as sub-cubic planar graphs. We derive a polynomial-time algorithm that takes (i) a graph $G=(V,E)$ and (ii) a vertex modulator $S$ of $G$ to chair-free graphs as inputs, and checks whether $G$ has a monopolar partition $V=(C\uplus{}I)$ where set $S$ is contained in the cluster part. We build on this algorithm to develop fast exact exponential-time and parameterized algorithms for MONOPOLAR RECOGNITION. Our exact algorithm solves MONOPOLAR RECOGNITION in $\mathcal{O}^{\star}(1.3734^{n})$ time on input graphs with $n$ vertices, where the $\mathcal{O}^{\star}()$ notation hides polynomial factors. In fact, we solve the more general problems MONOPOLAR EXTENSTION and LIST-MONOPOLAR PARTITION in $\mathcal{O}^{\star}(1.3734^{n})$ time. These are the first improvements over the trivial $\mathcal{O}^{\star}(2^{n})$-time algorithms for all these problems. It is known that -- assuming ETH -- these problems cannot be solved in $\mathcal{O}^{\star}(2^{o(n)})$ time. Our FPT algorithms solve MONOPOLAR RECOGNITION in $\mathcal{O}^{\star}(3.076^{k_{v}})$ and $\mathcal{O}^{\star}(2.253^{k_{e}})$ time where $k_{v}$ and $k_{e}$ are, respectively, the sizes of the smallest vertex and edge modulators of the input graph to claw-free graphs. These results are a significant addition to the small number of FPT algorithms currently known for MONOPOLAR RECOGNITION.

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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