On the edge irregularity strength of disjoint union of certain graphs

For a simple graph G, a vertex labeling phi : V(G) -> {1, 2,..., k} is called a vertex k-labeling. The weight of an edge xy in G, denoted by w(phi)(xy), is the sum of the labels of end vertices x and y, i.e. w(phi),(xy) = phi(x) + phi(y). A vertex k-labeling is defined to be an edge irregular k-labeling of the graph G if for every two different edges e and f, there is w(phi)(e) not equal w(phi)(f). The minimum k for which graph G has an edge irregular k-labeling is called the edge irregularity strength of G, denoted by es(G). In this paper, we determine the exact value of edge irregularity strength of disjoint union of zigzag, grid and generalized sun graphs.