What's a good way to write “x does not divide y”?

Question

The way I currently do it is $x \not | y$, which looks awful. There's got to be something better available.

Answer 1

$x\nmid y$ saves the day.

Answer 2

An alternative to \nmid is to use the \centernot command from the centernot package. The resulting \centernot\mid symbol aligns perfectly with \mid and has a more pronounced slash than \nmid:

(On the right, the image shows how the commands behave in sub/superscript.)

Answer 3

Another good looking (best to me) and easy option is to use the command \notdivides from the mathabx package. The code

\documentclass{article}
\usepackage{mathabx}
\begin{document}
\[ \prod_{a \notdivides b}^{a \notdivides b} a \notdivides b \]
\end{document}

creates the output

The negating line is longer than \nmid's but shorter than \centernot's.

Answer 4

$x \mod{y} \neq 0$ ;)

Answer 5

One possibility to assert, in symbols, that "a divides b" would be to use the MnSymbol package and then use $a \divides b$ (or $a \ndivides b$ for doesn't divide).

As I am typing a good deal of ring theory, I'm using those all the time.