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On the 2-independence subdivision number of graphs | ||
Communications in Combinatorics and Optimization | ||
مقاله 11، دوره 7، شماره 1، شهریور 2022، صفحه 105-112 اصل مقاله (353.36 K) | ||
نوع مقاله: Original paper | ||
شناسه دیجیتال (DOI): 10.22049/cco.2021.27060.1186 | ||
نویسندگان | ||
Nacéra Meddah* 1؛ Mostafa Blidia2؛ Mustapha Chellali3 | ||
1Department of Mathematics University of Blida B.P. 270, Blida, Algeria | ||
2Department of Mathematics, University of Blida 1. B.P. 270, Blida, Algeria | ||
3Department of Mathematics University of Blida 1, B.P. 270, Blida, Algeria | ||
چکیده | ||
A subset $S$ of vertices in a graph $G=(V,E)$ is $2$-independent if every vertex of $S$ has at most one neighbor in $S.$ The $2$-independence number is the maximum cardinality of a $2$-independent set of $G.$ In this paper, we initiate the study of the $2$-independence subdivision number $\mathrm{sd}% _{\beta _{2}}(G)$ defined as the minimum number of edges that must be subdivided (each edge in $G$ can be subdivided at most once) in order to increase the $2$-independence number. We first show that for every connected graph $G$ of order at least three, $1\leq \mathrm{sd}_{\beta _{2}}(G)\leq 2,$ and we give a necessary and sufficient condition for graphs $G$ attaining each bound. Moreover, restricted to the class of trees, we provide a constructive characterization of all trees $T$ with $\mathrm{sd}_{\beta _{2}}(T)=2,$ and we show that such a characterization suggests an algorithm that determines whether a tree $T$\ has\textrm{\ }$\mathrm{sd}_{\beta _{2}}(T)=2$\ or $\mathrm{sd}_{\beta _{2}}(T)=1$\ in polynomial time. | ||
کلیدواژهها | ||
Trees؛ 2-independence؛ subdivision numbers | ||
مراجع | ||
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