V4-cordial graphs

For any abelian group A, a graph G is said to be A-cordial if there exists a labeling f : V(G)→A such that for every a,b ∈ A we have |va −vb| ? 1 and (2) |ea −eb| ? 1, where va and ea respectively denote the number of vertices and edges having particular label a. In the present work we investigate a necessary condition for an Eulerian graph to be V4-cordial. In addition to this we show that all trees except P4 and P5 are V4-cordial and the cycle Cn is V4-cordial if and only if n # 4 or 5 or n # 2(mod 4).