Monus

In mathematics, monus is an operator on certain commutative monoids that are not groups. A commutative monoid on which a monus operator is defined is called a commutative monoid with monus, or CMM. The monus operator may be denoted with the minus sign, "${\displaystyle -}$", because the natural numbers are a CMM under subtraction. It is also denoted with a dotted minus sign, "${\displaystyle \mathbin {\dot {-}} }$", to distinguish it from the standard subtraction operator.