The competition number of a generalized line graph is at most two
نویسندگان
چکیده
In 1982, Opsut showed that the competition number of a line graph is at most two and gave a necessary and sufficient condition for the competition number of a line graph being one. In this paper, we generalize this result to the competition numbers of generalized line graphs, that is, we show that the competition number of a generalized line graph is at most two, and give necessary conditions and sufficient conditions for the competition number of a generalized line graph being one.
منابع مشابه
O ct 2 01 1 The competition number of a generalized line graph is at most two
In 1982, Opsut showed that the competition number of a line graph is at most two and gave a necessary and sufficient condition for the competition number of a line graph being one. In this note, we generalize this result to the competition numbers of generalized line graphs, that is, we show that the competition number of a generalized line graph is at most two, and give necessary conditions an...
متن کاملLine completion number of grid graph Pn × Pm
The concept of super line graph was introduced in the year 1995 by Bagga, Beineke and Varma. Given a graph with at least r edges, the super line graph of index r, Lr(G), has as its vertices the sets of r-edges of G, with two adjacent if there is an edge in one set adjacent to an edge in the other set. The line completion number lc(G) of a graph G is the least positive integer r for which Lr(G) ...
متن کاملOn generalized atom-bond connectivity index of cacti
The generalized atom-bond connectivity index of a graph G is denoted by ABCa(G) and defined as the sum of weights ((d(u)+d(v)-2)/d(u)d(v))aa$ over all edges uv∊G. A cactus is a graph in which any two cycles have at most one common vertex. In this paper, we compute sharp bounds for ABCa index for cacti of order $n$ ...
متن کاملOn Generalized Coprime Graphs
Paul Erdos defined the concept of coprime graph and studied about cycles in coprime graphs. In this paper this concept is generalized and a new graph called Generalized coprime graph is introduced. Having observed certain basic properties of the new graph it is proved that the chromatic number and the clique number of some generalized coprime graphs are equal.
متن کاملOn computing the general Narumi-Katayama index of some graphs
The Narumi-Katayama index was the first topological index defined by the product of some graph theoretical quantities. Let $G$ be a simple graph with vertex set $V = {v_1,ldots, v_n }$ and $d(v)$ be the degree of vertex $v$ in the graph $G$. The Narumi-Katayama index is defined as $NK(G) = prod_{vin V}d(v)$. In this paper, the Narumi-Katayama index is generalized using a $n$-ve...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Discrete Mathematics & Theoretical Computer Science
دوره 14 شماره
صفحات -
تاریخ انتشار 2012