When using `\not`

together with wider symbols such as `\Leftrightarrow`

the diagonal line produced by `\not`

is placed too far to the left. How can the line be properly aligned?

For example the following code

```
\documentclass{article}
\begin{document}
\(\not\subset\)% Looks good
\(\not\approx\)% Looks good
\(\not\leftrightarrow\)% \not line is too far to the left
\(\not\Leftrightarrow\)% \not line is too far to the left
\end{document}
```

produces the following output where the last two symbols has got a misaligned diagonal line

Also, maybe the lines may need other changes than alignment to look good.

## Best Answer

The

`\not`

symbol typesets a zero width character which protrudes on the right and so it is apt to be superimposed only on certain characters having a suitable width (the equal sign, for example); since the two arrows are wider than the equal sign, the alignment is not optimal. A solution is to push the`\not`

a bit on the right and backspacing for the same amount:You might also consider the set of "negated arrows" provided by

amssymb; the names are the same that I chose:Try both and choose what suits your taste. If you already load

amssymbuse`\renewcommand`

instead of`\newcommand`

.One can also define a

`\xnot`

command that gives to the symbol the width of the equal sign and use a standard method for superimposing symbols:Now

`\xnot\leftrightarrow`

gives the same result as the "definition by hand" before. The strange`\mathrel`

after`\not`

has its explanation in the fact that TeX never adds space between two relation math atoms. Thanks to Martin for having suggested this method. Thecenternotpackage does something similar.