In this paper we study the length of the longest induced cycle in the unitary Cayley graph Xn = Cay(Zn;Un), where Un is the group of units in Zn. Using residues modulo the primes dividing n, we introduce a representation of the vertices that reduces the problem to a purely combinatorial question of comparing strings of symbols. This representation allows us to prove that the multiplicity of eac...

In this note we obtain the energy of unitary Cayley graph Xn which extends a result of R. Balakrishnan for power of a prime and also determine when they are hyperenergetic. We also prove that E(Xn) 2(n−1) ≥ 2 4k , where k is the number of distinct prime divisors of n. Thus the ratio E(Xn) 2(n−1) , measuring the degree of hyperenergeticity of Xn, grows exponentially with k.

A signed graph (or sigraph in short) is an ordered pair S = (Su, σ), where Su is a graph G = (V,E) and σ : E → {+,−} is a function from the edge set E of Su into the set {+,−}. For a positive integer n > 1, the unitary Cayley graph Xn is the graph whose vertex set is Zn, the integers modulo n and if Un denotes set of all units of the ring Zn, then two vertices a, b are adjacent if and only if a...

The unitary Cayley graph Xn has vertex set Zn = {0, 1, . . . , n−1}. Vertices a, b are adjacent, if gcd(a− b, n) = 1. For Xn the chromatic number, the clique number, the independence number, the diameter and the vertex connectivity are determined. We decide on the perfectness of Xn and show that all nonzero eigenvalues of Xn are integers dividing the value φ(n) of the Euler function.

Let \({E}_{n}\) be the ring of Eisenstein integers modulo \(n\). We denote by \(G({E}_{n})\) and \(G_{{E}_{n}}\), unit graph unitary Cayley \({E}_{n}\), respectively. In this paper, we obtain value diameter, girth, clique number chromatic these graphs. also prove that for each \(n>1\), graphs \(G(E_{n})\) \(G_{E_{n}}\) are Hamiltonian.

The purpose of this paper is the study of Cayley graph associated to a semihypergroup(or hypergroup). In this regards first  we associate a Cayley graph to every semihypergroup and then we study theproperties of this graph, such as  Hamiltonian cycles in this  graph.  Also, by some of examples we will illustrate  the properties and behavior of  these Cayley  graphs, in particulars we show that ...