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). F

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.