So how do you tell TeX where the ends of sentences are? I rather like the simple interface that is 'press space bar twice'. Do I have to put something on abbreviations instead?
TeX has a rather unintuitive trick for this. If you have a period immediately after a word followed by whitespace, it is taken to mark the end of a sentence. In order to indicate that a period does not end a sentence, you prefix the space by \@, for example, in `Cf.\@ Something`.
Just in case that sounds too simple, there is an exception for initials: `P. G. Wodehouse` is treated the same as `P.\@ G.\@ Wodehouse`. If you want to cancel this, prefix the period by `\@`.
This kind of thing makes Latex a hard sell to a general audience.
TeX considers a period to be the end of a sentence unless it's preceded by a capital letter (in which case it assumes it's an initial or part of an acronym).
For abbreviations, you should explicitly insert a space control sequence (\<space>) or a non-breaking space (~) after the period.
