For school geometry, I would like to be able to write “A-P-B” to mean that a point P is between the points A and B. However, `$A-P-B$` gives the spacing of the minus operator, and I do not want the extra inserted space; and `$A$--$B$--$C$` sometimes gets broken across two lines. 

This code produces the output I want.

```
\documentclass[12pt]{amsart}
\begin{document}

Point $P$ is \emph{between} points $A$ and $B$ is 
notated $A$\nobreakdash--$P$\nobreakdash--$B$.

$\overline{AB} = \{ A \} \cup \{ B\ } \cup 
\{ P \mid A\text{--}P\text{--}C \}$.
\end{document}

```

Hopefully, there is a better way to accomplish this.

But if this *is* the right approach, then I would like help defineing something in my preface so I don't have to type it out all the time. 
One possibility would be 
 \newcommand{\Betw}{\nobreakdash--} % à la the AMS documentation.
and then write `$A$\Betw$P$\Betw$B$`, but that isn't really much better.

I'd rather define something (a trinary operator?) where I could input (something like) `$\Betw{APB}$` but I don't know how to define an operator/command like that.

I'm open to whatever suggestions, declarations, techniques or packages you might offer, but I need to use the A-P-B notation.

---

Note that `\between` is already defined as something else.