“…It was Anderson and Livingston (in [6]) who introduced the zero-divisor graph of a commutative ring and started the study of the relationship between ring-theoretic properties and graph-theoretic ones. Since then, zero-divisor graphs of commutative rings have attracted the attention of several researchers (see, for instance, [1,3,4,5,6,7,10,11,16,17]). It was proved, among other things, that Γ(R) is connected with diam(Γ(R)) ≤ 3 and gr(Γ(R)) ∈ {3, 4, ∞}.…”