arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1407.4593cs.DM
收藏

无$(P_5+kP_2)$图在多项式时间上的加权有效控制

Weighted Efficient Domination for $(P_5+kP_2)$-Free Graphs in Polynomial Time

Andreas Brandstadt, Vassilis Giakoumakis

摘要:

设$G$是一个有限无向图。一个顶点{ \em支配}它自己和它在$G$中的所有邻居。一个顶点集$D$是$G$的{ \em有效控制集}(简称\emph{e.d.} \),如果$G$的每个顶点都被$D$的一个顶点控制. \emph{Efficient Domination}(ED)问题,它要求存在一个ED。在$G$中,即使对于非常有限图类,例如对于无爪图、弦图和无$2P_3$图(因此,对于无$P_7$图),已知是\NP完全的。我们称一个图$F$为{ \em线性森林},如果$F$是无圈无爪的,即,它的组成部分是路径。因此,当$F$不是线性森林时,ED问题对于无$F$的图仍然是\NP完全的.令WED表示要求ed的ED问题的顶点加权版本最小的重量,如果有的话。本文证明了对于每个固定的$k$,$(P_5+kP_2)$ -free图的WED在多项式时间内是可解的,这解决了一个公开问题,并且利用模分解,我们改进了已知的$(P_4+P_2)$ -free图、$(P_6,S_{1,2,2})$ -free图和$(2P_3,S_{1,2,2})$ -free图的WED的时间界,简化了证明.对于$F$ -free图,唯一剩下的开放情况是$P_6$ -free图上的WED.

英文摘要:

Let $G$ be a finite undirected graph. A vertex {\em dominates} itself and all its neighbors in $G$. A vertex set $D$ is an {\em efficient dominating set} (\emph{e.d.}\ for short) of $G$ if every vertex of $G$ is dominated by exactly one vertex of $D$. The \emph{Efficient Domination} (ED) problem, which asks for the existence of an e.d.\ in $G$, is known to be \NP-complete even for very restricted graph classes such as for claw-free graphs, for chordal graphs and for $2P_3$-free graphs (and thus, for $P_7$-free graphs). We call a graph $F$ a {\em linear forest} if $F$ is cycle- and claw-free, i.e., its components are paths. Thus, the ED problem remains \NP-complete for $F$-free graphs, whenever $F$ is not a linear forest. Let WED denote the vertex-weighted version of the ED problem asking for an e.d. of minimum weight if one exists. In this paper, we show that WED is solvable in polynomial time for $(P_5+kP_2)$-free graphs for every fixed $k$, which solves an open problem, and, using modular decomposition, we improve known time bounds for WED on $(P_4+P_2)$-free graphs, $(P_6,S_{1,2,2})$-free graphs, and on $(2P_3,S_{1,2,2})$-free graphs and simplify proofs. For $F$-free graphs, the only remaining open case is WED on $P_6$-free graphs.

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。

↑