On 2-Domination Number of Some Graphs

Abstract

Domination and 2-domination numbers are defined only for graphs with non-isolated vertices. In a Graph G = (V, E) each vertex is said to dominate every vertex in its closed neighborhood. In a graph G, a subset S of V(G) is called a 2-dominating set of G if every vertex in v ∈ V, is in V-S and has atleast two neighbors in S. The smallest cardinality of a 2-dominating set of G is known as the 2-domination number γ2(G). In this paper, we find 2-dominating set of some special graphs and also find the 2-domination number of graphs.