I have a boolean expression field, where the user can enter a variable name and then perform one of 12 boolean operations on it. For reasons related to the rest of the UI, I cannot make the field very wide.
As such, I have designed a field that only shows a symbol - but when the user expands the drop-down, he can see the explanations for all the symbols.
But now, my boss wants to add new boolean operations - and I have difficulty coming up with symbols for them. I proposed an alternative solution, but he refused and wanted to keep the tiny dropdown with symbols.
Two of the boolean expressions are "empty value" and "not empty value." The symbol for empty value is easy - ∅. But what is the opposite?