Name this binary operation on $\Bbb N$ An operation $\ominus$ for the natural numbers is defined as follows:
$$a\ominus 0 = 0\ominus a = a\\S(a)\ominus S(b) = a\ominus b$$
Here $S$ is the successor function. The operation $a\ominus b$ is equivalent in value to $|a-b|$, except negative numbers, absolute value, and subtraction need not be defined. Here are some examples:
$$4\ominus 2 = S(3)\ominus S(1) = 3\ominus 1 = S(2)\ominus S(0) = 2\ominus 0 = 2\\2\ominus 4 = S(1)\ominus S(3) = 1\ominus 3 = S(0)\ominus S(2) = 0\ominus 2 = 2$$

Question: Does this operation have a common name or symbol?


"Distance" or "Difference" come to mind, as $a\ominus b$ is the difference between $a$ and $b$.
$\Delta a b$ is a notation that's sometimes used to express the difference between $a$ and $b$, particularly in physics.
