Tree-Adjoining Grammars

Aravind K. Joshi

in The Oxford Handbook of Computational Linguistics

Published in print January 2005 | ISBN: 9780199276349
Published online September 2012 | e-ISBN: 9780191743573 | DOI:

Series: Oxford Handbooks in Linguistics

 Tree-Adjoining Grammars

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Tree-adjoining grammar (TAG) and lexicalized tree-adjoining grammar (LTAG), have endured extensive study, in terms of formal properties and linguistic relevance. TAG and LTAG are formally equivalent. Structured trees, rather than strings, are manipulated by LTAG. The process of using structured elements as elementary to formal systems, facilitates the construction of formalisms whose studies relate directly to strong generative capacity (structural description), more linguistically relevant than the weak kind (string sets) each grammar formalisn specifies a domain of locality, a space over which various dependencies are specified. Key properties of LTAG include an extended domain of locality (EDL), which allows factoring recursion from domain of dependency (FRD), thereby, localizing all dependencies. Most modern formalisms, especially those with NL relevance, are lexicalized in a sense. Categorical grammars, especially combinatory categorical grammars (CCG), are also proximate to LATG. The key to comprehending TAG and LTAG, lies in realizing the notion of strong generative capacity of grammar formalisms.

Keywords: structured; tree; string; domain; grammar; formal

Article.  4979 words. 

Subjects: Computational Linguistics

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