I found this regex statement at http://en.wikipedia.org/wiki/Sentence_boundary_disambiguation for Sentence boundary disambiguation, but am not able to use it in a Ruby split statment. I'm not too good with regex so maybe I am missing something? This is statment:
((?<=[a-z0-9)][.?!])|(?<=[a-z0-9][.?!]\"))(\s|\r\n)(?=\"?[A-Z])
and this is what I tried in Ruby, but no go:
text.split("((?<=[a-z0-9)][.?!])|(?<=[a-z0-9][.?!]\"))(\s|\r\n)(?=\"?[A-Z])")
This should work in Ruby 1.9, or in Ruby 1.8 if you compiled it with the Oniguruma regex engine (which is standard in Ruby 1.9):
result = text.split(/((?<=[a-z0-9)][.?!])|(?<=[a-z0-9][.?!]"))\s+(?="?[A-Z])/)
The difference is that your code passes a literal string to split(), while this code passes a literal regex.
It won't work using the classic Ruby regex engine (which is standard in Ruby 1.8) because it doesn't support lookbehind.
I also modified the regular expression. I replaced (\s|\r\n) with \s+. My regex also splits sentences that have multiple spaces between them (typing two spaces after a sentence is common in many cultures) and/or multiple line breaks between them (delimiting paragraphs).
When working with Unicode text, a further improvement would be to replace a-z with \p{Ll}\p{Lo}, A-Z with \p{Lu}\p{Lt}\p{Lo}, and 0-9 with \p{N} in the various character classes in your regex. The character class with punctuation symbols can be expaned similarly. That'll need a bit more research because there's no Unicode property for end-of-sentence punctuation.