Domination Parameters of a Graph with Added Vertex
نویسنده
چکیده
Let G = (V,E) be a graph. A subset D ⊆ V is a total dominating set of G if for every vertex y ∈ V there is a vertex x ∈ D with xy ∈ E. A subset D ⊆ V is a strong dominating set of G if for every vertex y ∈ V − D there is a vertex x ∈ D with xy ∈ E and deg G (x) ≥ deg G (y). The total domination number γt(G) (the strong domination number γS(G)) is defined as the minimum cardinality of a total dominating set (a strong dominating set) of G. The concept of total domination was first defined by Cockayne, Dawes and Hedetniemi in 1980 [1], while the strong domination was introduced by Sampathkumar and Pushpa Latha in 1996 [3]. By a subdivision of an edge uv ∈ E we mean removing edge uv, adding a new vertex x, and adding edges ux and vx. A graph obtained from G by subdivision an edge uv ∈ E is denoted by G⊕ uxvx. The behaviour of the total domination number and the strong domination number of a graph G⊕ uxvx is developed.
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