Definition:Modulo Subtraction/Also denoted as

Modulo Subtraction: Also denoted as

Although the operation of subtraction modulo $m$ is denoted by the symbol $-_m$, if there is no danger of confusion, the conventional subtraction symbol $-$ is often used instead.

The notation for subtraction of two integers modulo $m$ is not usually $\eqclass a m -_m \eqclass b m$.

What is more normally seen is $a - b \pmod m$.

Sources

• 1965: J.A. Green: Sets and Groups ... (previous) ... (next): $\S 2.6$. Algebra of congruences
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): congruence modulo $n$
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): congruence modulo $n$