In a ring "R" the set of elements for which the zero-product rule does "not" hold are called the zero divisors of the ring, denoted by "Z" ("R").
In a ring "R" the elements for which the zero-product rule does "not" hold are called the zero divisors of the ring. The set of zero divisors, with 0 adjoined to it, may be denoted by "Z" ("R").