hyphenate even when it creates overfull hboxes

Question

Is there a way to force hyphenation even when it would generate overfull hboxes? I read here (texfaq.org) that when tex can't find a resolution that doesn't overfill the line, it just gives up with a warning. I have many situations in my document where a word hangs over the line, but it could be hyphenated to hang less far over (oftentimes much less far). Explicitly adding hyphenation marks doesn't help, I guess because the line would still be overfull.

Update with example

Ok, I guess this is an ill-formed question because my understanding of the texfaq article must have been incorrect. I'll explain what I think is happening in case either

• someone else makes the same mistake I did, or
• someone can correct my further misunderstanding(s).

Here's an example showing that tex does indeed hyphenate even when hboxes would be overfull. (I don't know if it matters that I'm using the cleveref package, but I am so I included it.)

Note: The explicit settings of textwidth and hyphenation are just for the purposes of this example.

\documentclass[draft]{amsbook}
\textwidth=49mm

\usepackage[english]{babel}
\usepackage[capitalise]{cleveref}

\newtheorem{corollary}{Corollary}

\hyphenation{corol-lary}
\begin{document}

\noindent
aaaaaaaaaaaaaaaaaaaaaaaaaa \cref{testcor}.

\begin{corollary}\label{testcor}
  a a a a a a a a a a a a a a 
\end{corollary}

\setcounter{corollary}{999}

\noindent
aaaaaaaaaaaaaaaaaaaaa \cref{testcor-b}.

\begin{corollary}\label{testcor-b}
  a a a a a a a a a a a a a a 
\end{corollary}

\end{document}

The output looks like this:

In the line referring to Corollary 1, there is hyphenation even though the hbox is overfull. In the line referring to Corollary 1000, no hyphenation occurs because it's too close to the end of the word. Furthermore, tex doesn't separate the number 1000 from the word, and that is the desired behavior.

I don't actually have 1000 corollaries in my document, but I do have numbers like 3.4.21 to refer to corollary 21 of section 4 of chapter 3. Looking again, most of my long overfull hboxes are because the numbers are so long. I suppose there's nothing to be done about that other than \sloppy (or changing \tolerance some other way) or rewording.

Answer 1

\hyphenation{corol-lary}

doesn't actually do anything as that is the default. If you allow a few more hyphenation points

\hyphenation{cor-ol-l-ary}

You get a better lienbreak:

Well I say it's better there is no right and wrong here, but breaking after the double l doesn't seem too bad to me.

Or you can keep the default hyphenation, but allow a bit of space around the cref-inserted word. I don't know the package that well so I added the space as part of the word (there may be a better interface). If you add

 \Crefname{corollary}{\hspace{0pt plus 1pt}Corollary\hspace{0pt plus 1pt}}{Corollaries}%

Then you get