Definition:Congruence Modulo an Ideal

Definition
Let $\left({R, +, \circ}\right)$ be a ring, and let $J$ be an ideal of $R$.

The notation:


 * $a \equiv b \pmod J$

is used to mean:


 * $a + \left({-b}\right) \in J$

Sometimes the notation:


 * $a \left({J}\right) b$

is used.