Definition:Proper Zero Divisor

Definition
Let $\left({R, +, \circ}\right)$ be a ring.

A proper zero divisor of $R$ is an element $x \in R^*$ such that:


 * $\exists y \in R^*: x \circ y = 0_R$

where $R^*$ is defined as $R \setminus \left\{{0_R}\right\}$.

That is, it is a zero divisor of $R$ which is specifically not $0_R$.

The presence of a proper zero divisor in a ring means that the product of two elements of the ring may be zero even if neither factor is zero.

That is, if $R$ has proper zero divisors, then $\left({R^*, \circ}\right)$ is not closed.

Also see

 * Zero Divisor