Mathematical symbol for "indifference" Is there any mathematical symbol for the word "indifferent". I mean that if I want to say if $x$ > 0, the machine can indifferently choose between $y$ or $z$. I want to express the last part in a mathematical notation. I know that in economics, we use `~` to denote indifference of preferences. Is there any general mathematical notation for that?

What you seem to want is an xor-decision (exclusive or). This is the logical operation that means "at least one, either one or the other, but not both at once". We can write it as a table

$$\begin{array}{|c|cc|}\hline\oplus&0&1\\\\\hline0&0&1\\\1&1&0\\\\\hline\end{array}$$

If the number 1 means "chosen" and 0 "not chosen" and

1 in the table means "OK" and 0 in the table means "Not OK".

May seem confusing with the symbols and numbers but in mathematics and computing being a bit extra pedantic is good to know precisely what we are talking about and not risking to screw things up.