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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.

skan
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    What exactly do you mean by "depend on"? – William Stagner Jan 28 '16 at 20:28
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    Depending on what you mean, you could use $\frac{dy}{dx}=0$ – Jürgen Sukumaran Jan 28 '16 at 20:31
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    Is it really necessary to have notation for this? (I'm not being snappish, I just am curious.) Do you need to say it dozens of times or something? – rschwieb Jan 28 '16 at 20:46
  • If there are three variables $x_1$, $x_2$ and $x_3$ that $y$ could depend on, you might write something like $y = y(x_1,x_2)$ to indicate that $y$ depends only on $x_1$ and $x_2$, but not on $x_3$. If $x$ is the only variable, you might write $y = \text{const}$ or something like that. – David Jan 28 '16 at 21:01
  • @William Stagner Depend on means that if you modify the value of x then y also modifies its value. And if we were speaking about random variables it would mean that the distribution of y is different for different values of x – skan Jan 28 '16 at 22:38
  • What context is this writing in??? As a general rule I tend to assume variables are independent unless stated, however this does depend on the author. – Brevan Ellefsen Jan 29 '16 at 04:11
  • I just want to know it in general, if there exist such a symbol. – skan Jan 29 '16 at 19:01

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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: enter image description here

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.

Bernard
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skan
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    Not strange at all. My knowledge is micro-encyclopedic, and I never heard of this notation. – marty cohen Apr 19 '16 at 20:53
  • So, in this book it is "stochastic independence". https://en.wikipedia.org/wiki/Independence_(probability_theory) I suppose there would be another symbol when we talk about "linear independence" another for "algebraic indepencence" and yet more for other sorts of independence. – GEdgar Jul 09 '19 at 17:15