For any a ∈ R, the principal ideal generated by a is denoted by (a). Recall that an ideal I
of R is called a multiplication ideal if for every ideal J ⊆ I , there exists an ideal K with J = KI .
An ideal I of R is called weak join principal if (AI : I) = A+ (0 : I) for all A ∈ L(R). I is
called join principal if (A+ BI) : I = (A : I) + B, for all A, B ∈ L(R). An ideal I of R is called
a quasi-principal ideal [8, Exercise 10, Page 147] (or a principal element of L(R) [9]) if it
satisfies the identities