For any k ∈ N, a graph G = (V,E) is said to be Zk-magic if there exists a labeling l : E(G) −→ Zk − {0} such that the induced vertex set labeling l : V (G) −→ Zk defined by l(v) = ∑ u∈N(v) l(uv) is a constant map. For a given graph G, the set of all k ∈ Z+ for which G is Zk-magic is called the integer-magic spectrum of G and is denoted by IM(G). In this paper we will consider trees whose diamet...

For any h ∈ IN , a graph G = (V, E) is said to be h-magic if there exists a labeling l : E(G) → ZZ h − {0} such that the induced vertex set labeling l : V (G) → ZZ h defined by l(v) = ∑ uv∈E(G) l(uv) is a constant map. When this constant is 0 we call G a zero-sum h-magic graph. The null set of G is the set of all natural numbers h ∈ IN for which G admits a zero-sum h-magic labeling. In this pap...

For any kEN, a graph G = (V, E) is said to be ;:z k-magic if there exists a labeling Z: E( G) --+ ;:z k {OJ such that the induced vertex set labeling Z+: V (G) --+ ;:z k defined by Z+(v) = L Z(uv) uvEE(G) is a constant map. For a given graph G, the set of all kEN for which G is ;:z k-magic is called the integer-magic spectrum of G and is denoted by IM(G). In this paper we will consider the func...

A (p,q) graph G is called super edge-magic if there exists a bijective function f from V (G) ∪ E(G) to {1, 2,. .. , p + q} such that f (x) + f (xy) + f (y) is a constant k for every edge xy of G and f (V (G)) = {1, 2,. .. , p}. Furthermore, the super edge-magic deficiency of a graph G is either the minimum nonnegative integer n such that G ∪ nK 1 is super edge-magic or +∞ if there exists no suc...

In this paper, we generalize the concept of super edge-magic graph by introducing the new concept of super edge-magic models.

A graph G is called super edge-magic if there exists a bijective function f : V (G) ∪ E (G) → {1, 2, . . . , |V (G)|+ |E (G)|} such that f (V (G)) = {1, 2, . . . , |V (G)|} and f (u) + f (v) + f (uv) is a constant for each uv ∈ E (G). A graph G with isolated vertices is called pseudo super edge-magic if there exists a bijective function f : V (G) → {1, 2, . . . , |V (G)|} such that the set {f (...

A graph is magic if the edges can be labeled with nonnegative real numbers such that (i) different edges have distinct labels, and (ii) the sum of the labels of edges incident to each vertex is the same. Regular magic graphs are characterized herein by the nonappearance of certain bipartite subgraphs. This implies that line connectivity is a crucial property for characterizing regular magic gra...

Let G = (V,E) be a graph of order p and size q. It is known that if G is super edge-magic graph then q ≤ 2p− 3. Furthermore, if G is super edge-magic and q = 2p− 3, then the girth of G is 3. It is also known that if the girth of G is at least 4 and G is super edge-magic then q ≤ 2p − 5. In this paper we show that there are infinitely many graphs which are super edge-magic, have girth 5, and q =...

There are many results on edge-magic, and vertex-magic, labellings of finite graphs. Here we consider magic labellings of countably infinite graphs over abelian groups. We also give an example of a finite connected graph that is edge-magic over one, but not over all, abelian groups of the appropriate order.