Editing Generalized phrase structure grammar

'''Generalized phrase structure grammar''' ('''GPSG''') is a framework for describing the [[syntax]] and [[semantics]] of [[natural language]]s. It is a type of [[Constraint-based grammar|constraint-based]] [[phrase structure grammar]]. Constraint based grammars are based around defining certain syntactic processes as [[Grammaticality|ungrammatical]] for a given language and assuming everything not thus dismissed is grammatical within that language. Phrase structure grammars base their framework on constituency relationships, seeing the words in a sentence as ranked, with some words dominating the others. For example, in the sentence "The dog runs",  "runs" is seen as dominating "dog" since it is the main focus of the sentence. This view stands in contrast to [[dependency grammar|dependency grammars]], which base their assumed structure on the relationship between a single word in a sentence (the sentence head) and its dependents.<ref>{{cite book | first=Gerald | last=Gazdar | author2=Ewan H. Klein | author3=Geoffrey K. Pullum | author4=Ivan A. Sag | year=1985 | title=Generalized Phrase Structure Grammar | location=Oxford | publisher=Blackwell, and Cambridge, MA: Harvard University Press | isbn=978-0-674-34455-6 | url-access=registration | url=https://archive.org/details/generalizedphras00gazd }}</ref>  

== Origins ==
GPSG was initially developed in the late 1970s by [[Gerald Gazdar]]. Other contributors include [[Ewan Klein]], [[Ivan Sag]], and [[Geoffrey Pullum]]. Their book ''Generalized Phrase Structure Grammar'', published in 1985, is the main monograph on GPSG, especially as it applies to English syntax. GPSG was in part a reaction against [[transformational grammar|transformational theories of syntax]]. In fact, the notational extensions to [[context-free grammars]] (CFGs) developed in GPSG are claimed to make transformations redundant.<ref>{{cite book | first=Gerald | last=Gazdar | author2=Ewan H. Klein | author3=Geoffrey K. Pullum | author4=Ivan A. Sag | year=1985 | title=Generalized Phrase Structure Grammar | location=Oxford | publisher=Blackwell, and Cambridge, MA: Harvard University Press | isbn=978-0-674-34455-6 | url-access=registration | url=https://archive.org/details/generalizedphras00gazd }}</ref> 

== Goals ==
One of the chief goals of GPSG is to show that the syntax of natural languages can be described by CFGs (written as [[ID/LP grammar]]s), with some suitable conventions intended to make writing such grammars easier for syntacticians. Among these conventions are a sophisticated [[feature structure]] system and so-called "meta-rules", which are rules generating the productions of a context-free grammar. GPSG further augments syntactic descriptions with semantic annotations that can be used to compute the compositional meaning of a sentence from its syntactic derivation tree.<ref>{{cite journal |last1=Ristad |first1=Eric |title=REVISED GENERALIZED PHRASE STRUCTURE GRAMMAR |url=http://aclweb.org/anthology/P87-1034 |website=aclweb.org |year=1987 |pages=243–250 |publisher=The Association for Computational Linguistics |doi=10.3115/981175.981209 |accessdate=16 December 2018|doi-access=free }}</ref> However, it has been argued (for example by [[Robert Berwick]]) that these extensions require [[parser|parsing]] algorithms of a higher order of [[Analysis of algorithms|computational complexity]] than those used for basic CFGs.

== Methodology ==
There are several ways to represent a sentence in Generalized Phrase Structure Grammar. One such method is a [[Parse tree|Syntax tree]], which represents all of the words in a sentence as leaf nodes in a parsing tree, as can be seen in the provided image. However, there are several other ways of representing sentences in GPSG. Certain constituents can be illustrated without drawing a full tree by placing the constituent in question inside of brackets like so:
[[File:GPSG_Syntax_Tree_Example.png|thumb|This file provides a simple example of a syntax tree that fits the Generalized Phrase Structure Grammar Framework.]] 
Who did you say that [[Hilary was fond of ] and [Leslie despised ]].<ref>{{cite journal |last1=Sag |first1=Ivan A. |title=Coordination, Extraction, and Generalized Phrase Structure Grammar |journal=Linguistic Inquiry |date=Spring 1982 |volume=13 |issue=2 |pages=329–336 |jstor=4178282 }}</ref>

== Counterarguments ==
Evidence soon emerged, however, that CFGs could not describe all of natural language (with examples in particular from Dutch and Swiss German [[cross-serial dependencies]]<ref>{{cite book |editor1-first=Ger J. |editor1-last=de Haan |editor2-first=Mieke |editor2-last=Trommelen |editor3-first=Wim |editor3-last=Zonneveld |last=Huybregts |first=Riny |chapter=The weak inadequacy of context-free phrase structure grammars |title=Van periferie naar kern |publisher=Foris |date=1984 |pages=81–99 |isbn=978-9067650199 }}</ref><ref>{{cite journal |last1=Shieber |first1=S. M. |title=Evidence against the context-freeness of natural language |journal=Linguistics and Philosophy |date=1985 |volume=8 |issue=3 |pages=333–343|doi=10.1007/BF00630917 |s2cid=222277837 |url=http://nrs.harvard.edu/urn-3:HUL.InstRepos:2026618 |url-access=subscription }}</ref>), and Gazdar, along with most other syntacticians, accepted that natural languages cannot in fact be adequately described by CFGs.<ref>{{cite book |last1=Gazdar |first1=Gerald |title=Natural Language Parsing and Linguistic Theories |volume=35 |pages=69–94 |chapter=Applicability of Indexed Grammars to Natural Languages |date=1988 |doi=10.1007/978-94-009-1337-0_3|series=Studies in Linguistics and Philosophy |isbn=978-1-55608-056-2 }}</ref> As a result, Generalized Phrase Structure Grammar was soon abandoned as a framework for describing natural languages, although CFGs are still used in computing languages. Most of the syntactic innovations of GPSG were subsequently incorporated into [[head-driven phrase structure grammar]].

==See also==
* [[Lexical functional grammar]]
*[[Phrase structure grammar]]
* [[Transformational grammar]]
*[[Head-driven phrase structure grammar]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20040414163332/http://www.cogs.susx.ac.uk/lab/nlp/gazdar/gazdar.html Gerald Gazdar's profile on the University of Sussex Website]
*[https://academictree.org/linguistics/publications.php?pid=48357 A list of Gazdar's linguistics publications, including ones dealing with GPSG]

[[Category:Generative linguistics]]
[[Category:Grammar frameworks]]
[[Category:Syntactic theories]]
[[Category:Semantic theories]]