| Title: | On the minus domination number of graphs (English) | 
| Author: | Liu, Hailong | 
| Author: | Sun, Liang | 
| Language: | English | 
| Journal: | Czechoslovak Mathematical Journal | 
| ISSN: | 0011-4642 (print) | 
| ISSN: | 1572-9141 (online) | 
| Volume: | 54 | 
| Issue: | 4 | 
| Year: | 2004 | 
| Pages: | 883-887 | 
| Summary lang: | English | 
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| Category: | math | 
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| Summary: | Let $G = (V,E)$ be a simple graph. A $3$-valued function $f\:V(G)\rightarrow \lbrace -1,0,1\rbrace $ is said to be a minus dominating function if for every vertex $v\in V$, $f(N[v]) = \sum _{u\in N[v]}f(u)\ge 1$, where $N[v]$ is the closed neighborhood of $v$. The weight of a minus dominating function  $f$ on $G$ is $f(V) = \sum _{v\in V}f(v)$. The minus domination number of a graph $G$, denoted by $\gamma ^-(G)$, equals the minimum weight of a minus dominating function on $G$. In this paper, the following two results are obtained. (1) If $G$ is a bipartite graph of order $n$, then \[ \gamma ^-(G)\ge 4\bigl (\sqrt{n + 1}-1\bigr )-n. \] (2) For any negative integer  $k$ and any positive integer $m\ge 3$, there exists a graph  $G$ with girth  $m$ such that $\gamma ^-(G)\le k$. Therefore, two open problems about minus domination number are solved. (English) | 
| Keyword: | minus dominating function | 
| Keyword: | minus domination number | 
| MSC: | 05C69 | 
| idZBL: | Zbl 1080.05523 | 
| idMR: | MR2100001 | 
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| Date available: | 2009-09-24T11:18:33Z | 
| Last updated: | 2020-07-03 | 
| Stable URL: | http://hdl.handle.net/10338.dmlcz/127937 | 
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