The following is a minimal example of a problem I'm having with hyphenation.
Four score and seven years ago, shamelessness our forefathers
brought forth upon this continent a new nation.
It seems that for a single-word paragraph inside a narrow column, I can't convince LaTeX to hyphenate the word. The result when I typeset this document looks like this:
nent a new
The width of 18 mm is chosen to be narrower than the word "shamelessness." If I explicitly suggest a hyphenation, the word gets hyphenated. But implicit hyphenation doesn't happen, even though I did everything I could think of to encourage it, setting \hyphenpenalty to zero and explicitly providing a hyphenation for the word. However, when I insert the word at a random spot in a multi-line passage of text, it gets hyphenated.
Why is latex refusing to do the implicit hyphenation here, and what can I do to fix the problem?
[EDIT] Thanks, David Carlisle, for your comment. That answers my question.