(Apologies if this is a duplicate; I didn't see my question among the many overfull \hbox questions already asked.)
My TeX file had been typsetting without any problems for a few days, when suddenly it started to complain of an overfull \hbox at a line that I had not modified since the previous compile. (The output still looks fine to me, for the record.)
The line that causes the problems is
More precisely, let $\P^N$ denote the space of all quadrics in a projective space $\P^n$ (so $N= {n+2 \choose 2}-1$.)
and the warning message is
ERROR: ** Overfull \hbox (1.12373pt too wide) in paragraph at lines 164--164
--- TeX said ---
(amsmath) on input line 53.
--- HELP ---
Because it couldn't find a good place for a line break, TeX put more on this line than it should.
Can anyone diagnose this problem?
\hboxmessage is not an error, but only a warning; the error is due to\choose; withamsmaththere's the better\binom{n+2}{2}instead of{n+2\choose 2}. – egreg Feb 14 at 21:06