If I want to say x doesn't exist I would use the symbol $\nexists$
If I want to say x is a member of... I would use $\in$
But what's the symbol to say y doesn't depend on x?
I know I could write something like y$\neq$f(x) but I'm looking for a single symbol, something more compact, without the f northe parenthesis.
Does it exist?
In fact f(x) represents a function, and we could have a relationship without a function.
OK, the notation already exists, and I have found it.
The book "Bayesian Reasoning and Machine Learning" provides a mathematical notation list, where it says:
Then, this pi-like symbol, and the reversed pi mean that a variable is dependent or independent on other variable. I don't know if it's only used in a statistical framework or also in general in mathematics.
It's strange nobody knew it.