Sentence boundary disambiguation


Sentence boundary disambiguation, also known as sentence breaking, sentence boundary detection, and sentence segmentation, is the problem in natural language processing of deciding where sentences begin and end. Natural language processing tools often require their input to be divided into sentences; however, sentence boundary identification can be challenging due to the potential ambiguity of punctuation marks. In written English, a period may indicate the end of a sentence, or may denote an abbreviation, a decimal point, an ellipsis, or an email address, among other possibilities. About 47% of the periods in the Wall Street Journal corpus denote abbreviations. Question marks and exclamation marks can be similarly ambiguous due to use in emoticons, computer code, and slang.
Languages like Japanese and Chinese have unambiguous sentence-ending markers.

Strategies

The standard 'vanilla' approach to locate the end of a sentence:
This strategy gets about 95% of sentences correct. Things such as shortened names, e.g. "D. H. Lawrence", idiosyncratic orthographical spellings used for stylistic purposes and usage of non-standard punctuation in a text often fall under the remaining 5%.
Another approach is to automatically learn a set of rules from a set of documents where the sentence breaks are pre-marked. Solutions have been based on a maximum entropy model. The architecture uses a neural network to disambiguate sentence boundaries and achieves 98.5% accuracy.

Software

;Examples of use of Perl compatible regular expressions
;Online use, libraries, and APIs
;Toolkits that include sentence detection