FURTHER RESULTS ON K-PRODUCT CORDIAL LABELING

Let f be a map from V(G) to {0,1,..., k - 1} where k is an integer, 1 [less than or equal to] k [less than or equal to] |V(G)|. For each edge uv assign the label f(u)f(v)(mod k). f is called a k-product cordial labeling if |[v.sub.f](i) - [v.sub.f](j)| [less than or equal to] 1, and |[e.sub.f](i) - [e.sub.f](j)| [less than or equal to] 1, i,j [member of] {0,1,..., k - 1}, where [v.sub.f] (x) and [e.sub.f] (x) denote the number of vertices and edges respectively labeled with x (x = 0, 1,...,k - 1). In this paper, we investigate the k-product cordial behaviour of G + [??]. In addition, we find an upper bound of the size of connected k-product cordial graphs. KEYWORDS: Cordial labeling, product cordial labeling, k-product cordial labeling, 4-product cordial graph.