Let H = {A1, . . . , An, B1, . . . , Bn} be a collection of 2n subgraphs of the complete bipartite graph Kn,n. The collection H is called an orthogonal double cover (ODC) of Kn,n if each edge of Kn,nâ€¦ (More)

For a connected graph G of order |V (G)| â‰¥ 3 and a k-edge-weighting c : E(G) â†’ {1, 2, . . . , k} of the edges of G, the code, codec(v), of a vertex v of G is the ordered k-tuple (l1, l2, . . . , lk),â€¦ (More)

For a simple graph G with chromatic number x(G), the Nordhaus-Gaddum inequalities give upper and lower bounds for z(G)â€¢(G Â¢) and z(G)+ x(GC). Based on a characterization by Fink of the extremalâ€¦ (More)

For a graph G, let D(G) be the set of all strong digraphs D obtained by the orientations of G. The orientation number of G is â†’ d(G) = min {d(D) |D âˆˆ D(G)}, where d(D) denotes the diameter of theâ€¦ (More)

A twin edge k-coloring of a graph G is a proper edge k-coloring of G with the elements of Zk so that the induced vertex k-coloring, in which the color of a vertex v in G is the sum in Zk of theâ€¦ (More)

The use of metals and minerals is predominant in siddha system of medicine. As per siddha concept, peptic ulcer is known as Valigunmam, the basic abnormality appears to be the derangement ofâ€¦ (More)