K-PRODUCT CORDIAL LABELING OF FAN GRAPHS

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) - [c.sub.f] < 1, i, j [member of] {0,1,k - 1}, where [V.sub.f] (x) and [member of] (x) denote the number of vertices and edges respectively labeled with x (x = 0,1,..., k - 1). In this paper we prove that fan [F.sub.n] and double fan [DF.sub.n] when k=4 and 5 admit k-product cordial labeling. Keywords: cordial labeling, product cordial labeling, k-product cordial labeling, 4-product cordial graph, 5-product cordial graph. AMS Subject Classification: 05C78.