Thoughout this paper, Γ denotes a group with identity e and G denotes a
graph with order p and size q. Terms not defined here are used in the sense of
Apostol1,Harary3 and Herstein4.
Two integers a and b are said to be relatively prime if their greatest common
divisor is 1 viz., (a, b)=1. Relatively prime integers play a significant role in
both Analytic and Algebraic number theory. They motivated us to define order
prime graph OP(Γ), where Γ is a finite group. We hope that this definition
will be a foundation stone for a new development in Algebraic Graph Theory.
It is defined as a graph with V (OP(Γ))=Γ , where Γ is a finite group and two
vertices are adjacent in OP(Γ) if and only if their orders are relatively prime
in Γ.