Domination Parameters and Vertex-Contraction-Critical Graphs
Received:January 05, 2004  
Key Words: vertex-contraction   domination number   upper domination number   independent domination number   independence number.  
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Author NameAffiliation
CHEN Yi-chao Dept. of Math., Beijing Jiaotong University, Beijing 100044, China 
LIU Yu-xing Dept. of Math., Gannan Normal University, Ganzhou 341000, China 
SU Jian-ji Dept. of Math., Guangxi Normal University, Guilin 541004, China 
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Abstract:
      Let $G$ be a simple graph and $u,v\in V(G)$. The graph $G_{uv}$ is called the vertex-contraction of $G$, if we identify the vertices $u$ and $v$ and remove all resulting loops and duplicate edges. This paper deals with the relationship of domination parameters between $G_{uv}$ and $G$, and gets $\gamma(G_{uv})=\gamma(G)$ or $ \gamma(G_{uv})=\gamma(G)-1$, $\Gamma(G_{uv})=\Gamma(G)$ or $ \Gamma(G_{uv})=\Gamma(G)-1$, $\beta(G_{uv})=\beta(G)$ or $\beta(G_{uv})=\beta(G)-1$ . The sufficient and necessary conditions for $\gamma(G_{uv})=\gamma(G)-1$ and $\beta(G_{uv})=\beta(G)-1$ are also obtained.
Citation:
DOI:10.3770/j.issn:1000-341X.2006.03.026
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