Natural Language Processing with Python

Further Reading

Please consult http://www.nltk.org/ for further materials on this chapter, including HOWTOs feature structures, feature grammars, Earley parsing, and grammar test suites.

For an excellent introduction to the phenomenon of agreement, see (Corbett, 2006).

The earliest use of features in theoretical linguistics was designed to capture phonological properties of phonemes. For example, a sound like /b/ might be decomposed into the structure [+labial, +voice]. An important motivation was to capture generalizations across classes of segments, for example, that /n/ gets realized as /m/ preceding any +labial consonant. Within Chomskyan grammar, it was standard to use atomic features for phenomena such as agreement, and also to capture generalizations across syntactic categories, by analogy with phonology. A radical expansion of the use of features in theoretical syntax was advocated by Generalized Phrase Structure Grammar (GPSG; [Gazdar et al., 1985]), particularly in the use of features with complex values.

Coming more from the perspective of computational linguistics, (Kay, 1985) proposed that functional aspects of language could be captured by unification of attribute-value structures, and a similar approach was elaborated by (Grosz & Stickel, 1983) within the PATR-II formalism. Early work in Lexical-Functional grammar (LFG; [Kaplan & Bresnan, 1982]) introduced the notion of an f-structure that was primarily intended to represent the grammatical relations and predicate-argument ...