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Head-driven phrase structure grammar (HPSG) is a highly lexicalized,
constraint-based grammar Model-theoretic grammars, also known as constraint-based grammars, contrast with generative grammars in the way they define sets of sentences: they state constraints on syntactic structure rather than providing operations for generating syntactic ...
developed by Carl Pollard and
Ivan Sag Ivan Andrew Sag (November 9, 1949 – September 10, 2013) was an American linguist and cognitive scientist. He did research in areas of syntax and semantics as well as work in computational linguistics. Personal life Born in Alliance, Ohio on N ...
. It is a type of phrase structure grammar, as opposed to a
dependency grammar Dependency grammar (DG) is a class of modern grammatical theories that are all based on the dependency relation (as opposed to the ''constituency relation'' of phrase structure) and that can be traced back primarily to the work of Lucien Tesni� ...
, and it is the immediate successor to generalized phrase structure grammar. HPSG draws from other fields such as
computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
( data type theory and
knowledge representation Knowledge representation and reasoning (KRR, KR&R, KR²) is the field of artificial intelligence (AI) dedicated to representing information about the world in a form that a computer system can use to solve complex tasks such as diagnosing a medic ...
) and uses
Ferdinand de Saussure Ferdinand de Saussure (; ; 26 November 1857 – 22 February 1913) was a Swiss linguist, semiotician and philosopher. His ideas laid a foundation for many significant developments in both linguistics and semiotics in the 20th century. He is wide ...
's notion of the sign. It uses a uniform formalism and is organized in a modular way which makes it attractive for
natural language processing Natural language processing (NLP) is an interdisciplinary subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to proc ...
. An HPSG grammar includes principles and grammar rules and
lexicon A lexicon is the vocabulary of a language or branch of knowledge (such as nautical or medical). In linguistics, a lexicon is a language's inventory of lexemes. The word ''lexicon'' derives from Greek word (), neuter of () meaning 'of or fo ...
entries which are normally not considered to belong to a grammar. The formalism is based on lexicalism. This means that the lexicon is more than just a list of entries; it is in itself richly structured. Individual entries are marked with types. Types form a hierarchy. Early versions of the grammar were very lexicalized with few grammatical rules (schema). More recent research has tended to add more and richer rules, becoming more like
construction grammar Construction grammar (often abbreviated CxG) is a family of theories within the field of cognitive linguistics which posit that constructions, or learned pairings of linguistic patterns with meanings, are the fundamental building blocks of human ...
. The basic type HPSG deals with is the sign.
Word A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...
s and phrases are two different subtypes of sign. A word has two features: ''
HON Hon or HON may refer to: People * Han (surname) (Chinese: 韩/韓), also romanized Hon * Louis Hon (1924–2008), French footballer * Priscilla Hon (born 1998), Australian tennis player Other uses * Hon (Baltimore), a cultural stereotype of ...
' (the sound, the
phonetic Phonetics is a branch of linguistics that studies how humans produce and perceive sounds, or in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. ...
form) and '' YNSEM' (the
syntactic In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituency) ...
and
semantic Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and comput ...
information), both of which are split into subfeatures. Signs and rules are formalized as typed feature structures.


Sample grammar

HPSG generates strings by combining signs, which are defined by their location within a type hierarchy and by their internal feature structure, represented by attribute value matrices (AVMs). Pollard, Carl; Ivan A. Sag. (1994).
Head-driven phrase structure grammar
'. Chicago: University of Chicago Press.
Features take types or lists of types as their values, and these values may in turn have their own feature structure. Grammatical rules are largely expressed through the constraints signs place on one another. A sign's feature structure describes its phonological, syntactic, and semantic properties. In common notation, AVMs are written with features in upper case and types in italicized lower case. Numbered indices in an AVM represent token identical values. In the simplified AVM for the word (in this case the verb, not the noun as in "nice walks for the weekend") "walks" below, the verb's categorical information (CAT) is divided into features that describe it (HEAD) and features that describe its arguments (VALENCE). "Walks" is a sign of type ''word'' with a head of type ''verb''. As an intransitive verb, "walks" has no complement but requires a subject that is a third person singular noun. The semantic value of the subject (CONTENT) is co-indexed with the verb's only argument (the individual doing the walking). The following AVM for "she" represents a sign with a SYNSEM value that could fulfill those requirements. Signs of type ''phrase'' unify with one or more children and propagate information upward. The following AVM encodes the immediate dominance rule for a ''head-subj-phrase'', which requires two children: the head child (a verb) and a non-head child that fulfills the verb's SUBJ constraints. The end result is a sign with a verb head, empty subcategorization features, and a phonological value that orders the two children. Although the actual grammar of HPSG is composed entirely of feature structures, linguists often use trees to represent the unification of signs where the equivalent AVM would be unwieldy.


Implementations

Various
parsers Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term ''parsing'' comes from L ...
based on the HPSG formalism have been written and optimizations are currently being investigated. An example of a system analyzing
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
sentences is provided by the Freie Universität Berlin. In addition the CoreGram project of the Grammar Group of the Freie Universität Berlin provides open source grammars that were implemented in the TRALE system. Currently there are grammars for
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
, Danish,
Mandarin Chinese Mandarin (; ) is a group of Chinese (Sinitic) dialects that are natively spoken across most of northern and southwestern China. The group includes the Beijing dialect, the basis of the phonology of Standard Chinese, the official language ...
, Maltese, and Persian that share a common core and are publicly available. Large HPSG grammars of various languages are being developed in the Deep Linguistic Processing with HPSG Initiative ( DELPH-IN). Wide-coverage grammars of English, German, and Japanese are available under an open-source license. These grammars can be used with a variety of inter-compatible open-source HPSG parsers: LKB, PET, Ace, and ''agree''. All of these produce semantic representations in the format of “Minimal Recursion Semantics,” MRS. The declarative nature of the HPSG formalism means that these computational grammars can typically be used for both
parsing Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term ''parsing'' comes from ...
and generation (producing surface strings from semantic inputs). Treebanks, also distributed by DELPH-IN, are used to develop and test the grammars, as well as to train ranking models to decide on plausible interpretations when parsing (or realizations when generating). ''Enju'' is a freely available wide-coverage probabilistic HPSG parser for English developed by the Tsujii Laboratory at The University of Tokyo in
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
.Tsuji Lab: Enju parser home page
(retrieved Nov 24, 2009)


See also

* Lexical-functional grammar *
Minimal recursion semantics Minimal recursion semantics (MRS) is a framework for computational semantics. It can be implemented in typed feature structure formalisms such as head-driven phrase structure grammar and lexical functional grammar. It is suitable for computational ...
* Relational grammar *
Situation semantics In situation theory, situation semantics (pioneered by Jon Barwise and John Perry in the early 1980s) attempts to provide a solid theoretical foundation for reasoning about common-sense and real world situations, typically in the context of theor ...
*
Syntax In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure ( constituenc ...
* Transformational grammar * Type Description Language


References


Further reading

* Carl Pollard, Ivan A. Sag (1987): ''Information-based Syntax and Semantics. Volume 1: Fundamentals''. Stanford: CSLI Publications. * Carl Pollard, Ivan A. Sag (1994): ''Head-Driven Phrase Structure Grammar''. Chicago: University of Chicago Press.

* Ivan A. Sag,
Thomas Wasow Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (disambiguation) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Ap ...
, Emily M. Bender (2003): ''Syntactic Theory: a formal introduction, Second Edition''. Chicago: University of Chicago Press.

* *


External links


Stanford HPSG homepage
– includes on-line proceedings of an annual HPSG conference
Ohio State HPSG homepage

International Conference on Head-Driven Phrase Structure Grammar

DELPH-IN network for HPSG grammar development




* ttp://hpsg.fu-berlin.de/HPSG-Bib/ Bibliography of HPSG Publications
LaTeX package for drawing AVMs
– includes documentation {{DEFAULTSORT:Head-Driven Phrase Structure Grammar Generative linguistics Grammar frameworks Syntactic theories