"Does not depend on" symbol I've had a good hunt but can't seem to find a clear enough answer, so apologies for the potentially stupid question, but what is the symbol that would replace "does not depend on" in the line below?
$2x^2$ "does not depend on" $y$
Thanks very much,
Tom
 A: For instance, when you define some parameter $\alpha$ and do not say anything, it is assumed that it is just a constant. However, if instead you write $\alpha_n$, is should be clear that $\alpha$ depends on $n$. To emphasize this one might even write $\alpha = \alpha(n)$. Similarly, to show that $2x^2$ does not depend on $y$, you could write $2x^2 \ne f(x, y)$, or $2x^2 \ne f(y)$. However, most people would not state that one quantity $q$ does not depend on some other quantity $p$. In the modern literature, authors bother writing something only if $q$ depends on $p$.
A: This has been answered in another SE site:
What's the mathematical symbol to say "It doesn't depend on ..."?
The simple answer is that "X ⫫ Y"  means that X and Y are independent, while "X ⫪ Y" means they are dependent.  This looks like a pi and upside down pi, but the horizontal part seems to be wider.  When adding it in Google Docs, the name of the symbol is "double down tack" and "double up tack". 
I'd never seen this before, but was looking for just this symbol to describe some coding specs.
