The Dual Neighborhood Number of a Graph

A set S ⊆ V (G) is a neighborhood set of a graph G =( V, E), if G = v∈SN(v)� , whereN(v)� is the sub graph of a graph G induced by v and all vertices adjacent to v. The dual neighborhood number η +2 (G) = Min. {|S1|+ |S2| : S1 ,S 2 are two disjoint neighborhood set of G}. In this paper, we extended the concept of neighborhood number to dual neighborhood number and its relationship with other neighborhood related parameters are explored. Mathematics Subject Classification: 05C69, 05C70