Routledge Dictionary of Language and Linguistics.pdf

A-Z 503ReferencePollard, C. 1984. Head grammars. generalized phrase structure grammars and natural languages.Dissertation, Stanford, CA.Head-driven Phrase Structure Grammar(abbrev. HPSG)A generative theory of grammar from the family of unification grammars whichcombines elements of Generalized Phrase Structure Grammar (GPSG), FunctionalUnification Grammar and PATR Formalism. HPSG uses a comprehensive inventory ofdescriptive tools from unification grammar. As in Functional Unification Grammar, inHPSG all linguistic units are represented by feature structures, which are called ‘signs’by de Saussure. They contain features for the encoding of phonological, syntactic, andsemantic information ([PHON], [SYN], [SEM]). The links between the values of thesefeatures determine the grammatical correspondence between sounds and meaning. Thegrammar is likewise represented in the form of feature structures, which are linguisticwellformedness constraints on the signs. In contrast to Generalized Phrase StructureGrammar, the grammar of HPSG is heavily lexicalized, i.e. the lexicon, which isstructured hierarchically by the unification formalism, contains a large part of thesyntactic information. There are only a few syntactic rules. X-bar theory, especially theparallels between verb phrases and noun phrases, is used in such a way that complementbinding can be accomplished with just two rules, which connect the head categorycontaining the external argument to the bound argument. Likewise, one rule accounts foradjunct modification. Phrase structure rules are free of redundancy due to theformulation of general (universal) principles which are also encoded as feature structures.Revised versions of some principles of GPSG can be found in HPSG. Subcategorizationtakes place through the feature [SUBCAT]. Long-distance dependencies are captured bythe co-operation of feature transmission and grammatical principles. The organization ofthe grammar is borrowed from Functional Unification Grammar. The grammar is thedisjunction of all rules and all lexical entries, in conjunction with the grammaticalprinciples. Every wellformed sign must be compatible with the grammar. So far there arevery few grammatical descriptions using HPSG; however, there are experimentalcomputational linguistics systems which use it.