In electrical engineering, when speaking of boolean algebra, it is common to represent negation (¬ P) with an overline and logical and (P ∧ Q) with juxtaposition. In LaTeX, I was using the `\overline`

command in math mode for negation.

That worked well until I noticed that the lines over adjacent symbols were being combined. In HTML, this is like ¬ (P ∧ Q) becoming ¬ P ∧ ¬ Q, which is completely different.

As an example, consider this LaTeX source:

```
\documentclass[varwidth]{standalone}
\begin{document}
$\overline P \overline Q$
$\overline{P Q}$
$\overline P \ \overline Q$
\end{document}
```

It produces the following output:

`$\overline P \overline Q$`

should look different from `$\overline{P Q}$`

; the former should have two separate overlines and the latter should have a single overline that extends across both P and Q.

I can get close to what I want with `$\overline P \ \overline Q$`

, but that has two problems. First, it introduces extra space between the P and the Q that wouldn't otherwise be there. Second, it requires manually and explicitly identifying how things should be placed on the page, which is difficult, error prone, and (as I understand) against the philosophy of TeX in that I'm supposed to worry about semantics while TeX handles the layout.

Note that I can't use `\bar`

, because I often do need a single overline to stretch across both symbols (or even over a more complex sentence).

I'm guessing that the answer to my question is that I'm abusing `\overline`

, and that I should instead be using some other math-mode command that is already defined in amsmath or even in LaTeX itself. In any case, I'm avoiding complex macros etc. because I very much doubt that they're the right choice here (or if they are, then there's already a package for it).

Lastly, I'll point out that very similar questions have been asked before, but I haven't found a satisfying answer to this one. In particular this question is pretty much identical to mine, but the answer there is not without problems. I've described that solution along with a couple others in my answer below.

## Best Answer

You can use

`\widebar`

from`mathabx`

without changing all the symbol fonts.The code for importing the accent is taken (simplified) from this answer by Leo Liu. I added a new macro to cope with the

`amsmath`

impossibility of dealing with nested accents where the inner object has two accented items. The optional argument to`\cwidebar`

is used to fine tune the positioning.