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Dependency grammar

Dependency grammar

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Encyclopedia
Dependency grammar is a class of modern syntactic
Syntax
In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....

 theories that are all based on the dependency relation and that can be traced back primarily to the work of Lucien Tesnière
Lucien Tesnière
Lucien Tesnière was one of the most prominent and influential French linguists.Tesnière was born in Mont-Saint-Aignan on May 13, 1893...

. Dependency grammars are distinct from phrase structure grammar
Phrase structure grammar
The term phrase structure grammar was originally introduced by Noam Chomsky as the term for grammars as defined by phrase structure rules, i.e. rewrite rules of the type studied previously by Emil Post and Axel Thue...

s (=constituency grammars), since they lack phrasal nodes. Structure is determined by the relation between a word (a head) and its dependents. Dependency structures are flatter than constituency structures in part because they lack a finite verb phrase
Verb phrase
In linguistics, a verb phrase or VP is a syntactic unit composed of at least one verb and the dependents of that verb. One can distinguish between two types of VPs, finite VPs and non-finite VPs . While phrase structure grammars acknowledge both, dependency grammars reject the existence of a...

 constituent, and they are thus well suited to languages with free word order, such as Czech
Czech language
Czech is a West Slavic language with about 12 million native speakers; it is the majority language in the Czech Republic and spoken by Czechs worldwide. The language was known as Bohemian in English until the late 19th century...

 and Turkish
Turkish language
Turkish is a language spoken as a native language by over 83 million people worldwide, making it the most commonly spoken of the Turkic languages. Its speakers are located predominantly in Turkey and Northern Cyprus with smaller groups in Iraq, Greece, Bulgaria, the Republic of Macedonia, Kosovo,...

.

History


The notion of dependencies between grammatical units has existed since the earliest recorded grammars, e.g. Panini, and the dependency concept therefore arguably outdates the constituency notion by many centuries. Ibn Mada was the first grammarian to use the term dependency in the grammatical sense that we use it today. He was born in 1119 in Cordoba, studied in Sevilla and Ceuta, and died 1195 in Sevilla. In early modern times, the dependency concept seems to have coexisted side by side with the constituency concept, the latter having entered Latin, French, English and other grammars from the widespread study of term logic
Term logic
In philosophy, term logic, also known as traditional logic or aristotelian logic, is a loose name for the way of doing logic that began with Aristotle and that was dominant until the advent of modern predicate logic in the late nineteenth century...

 of antiquity.

Modern dependency grammars, however, begin primarily with the work of Lucien Tesnière. Tesnière was a Frenchman, a polyglot
Polyglot
Polyglot may refer to:*Polyglot , someone who uses many languages*Polyglot , a book that contains the same text in more than one language*Polyglot , a computer program that is valid in more than one programming language...

, and a professor of linguistics at the universities in Strasbourg and Montpellier. His major work Éléments de syntaxe structurale was published posthumously in 1959 - he died in in 1954. The basic approach to syntax he developed seems to have been seized upon independently by others in the 1960s and a number of other dependency-based grammars have gained prominence since those early works. Dependency grammar has generated a lot of interest in Germany in both theoretical syntax and language pedagogy. In recent years, the great development surrounding dependency-based theories has come from computational linguistics
Computational linguistics
Computational linguistics is an interdisciplinary field dealing with the statistical or rule-based modeling of natural language from a computational perspective....

. Dependency-based systems are increasingly being used to parse natural language and generate tree banks. Interest in dependency grammar is growing at present, the first international conference on dependency linguistics having taken place just recently (Depling 2011).

Dependency vs. constituency


Dependency is a one-to-one correspondence: For every element (e.g. word or morph) in the sentence, there is exactly one node in the structure of that sentence that corresponds to that element. The result of this one-to-one correspondence is that dependency grammars are word (or morph) grammars. All that exist are the elements and the dependencies that connect the elements into a structure. This situation should be compared with the constituency relation of phrase structure grammars. Constituency is a one-to-one-or-more correspondence, which means that given a sentence, for every element in that sentence, there are one or more nodes in the structure that correspond to that element. The result of this difference is that dependency structures are minimal compared to their constituency structure counterparts, since they tend to contain many fewer nodes.


These two trees illustrate just two possible ways to render the dependency and constituency relations. The dependency tree is an "ordered" tree, i.e. it reflects actual word order. Many dependency trees abstract away from linear order and focus just on hierarchical order, which means they do not show actual word order. The constituency tree follows the conventions of bare phrase structure
Minimalist program
In linguistics, the Minimalist Program is a major line of inquiry that has been developing inside generative grammar since the early nineties. It started with a 1993 paper by Noam Chomsky....

 (BPS), whereby the words themselves are employed as the node labels.

The distinction between dependency- and constituency-based grammars derives in a large part from the initial division of the clause. The constituency relation derives from an initial binary division, whereby the clause is split into a subject noun phrase
Noun phrase
In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....

 (NP) and a predicate
Predicate (grammar)
There are two competing notions of the predicate in theories of grammar. Traditional grammar tends to view a predicate as one of two main parts of a sentence, the other being the subject, which the predicate modifies. The other understanding of predicates is inspired from work in predicate calculus...

 verb phrase
Verb phrase
In linguistics, a verb phrase or VP is a syntactic unit composed of at least one verb and the dependents of that verb. One can distinguish between two types of VPs, finite VPs and non-finite VPs . While phrase structure grammars acknowledge both, dependency grammars reject the existence of a...

 (VP). This division is certainly present in the basic analysis of the clause that we find in the works of, for instance, Leonard Bloomfield
Leonard Bloomfield
Leonard Bloomfield was an American linguist who led the development of structural linguistics in the United States during the 1930s and the 1940s. His influential textbook Language, published in 1933, presented a comprehensive description of American structural linguistics...

 and Noam Chomsky
Noam Chomsky
Avram Noam Chomsky is an American linguist, philosopher, cognitive scientist, and activist. He is an Institute Professor and Professor in the Department of Linguistics & Philosophy at MIT, where he has worked for over 50 years. Chomsky has been described as the "father of modern linguistics" and...

. Tesnière, however, argued vehemently against this binary division, preferring instead to position the verb as the root of all clause structure. Tesnière's stance was that the subject-predicate division stems from term logic
Term logic
In philosophy, term logic, also known as traditional logic or aristotelian logic, is a loose name for the way of doing logic that began with Aristotle and that was dominant until the advent of modern predicate logic in the late nineteenth century...

 and has no place in linguistics. The importance of this distinction is that if one acknowledges the initial subject-predicate division in syntax as something real, then one is likely to go down the path of constituency grammar, whereas if one rejects this division, then the only alternative is to position the verb as the root of all structure, which means one has chosen the path of dependency grammar.

Strings and catenae


Tesnière emphasized that syntactic units are organized along two dimensions, the horizontal (precedence) dimension and the vertical (dominance) dimension. In this respect, acknowledging dependency-based structures encourages one to isolate units in the one or the other dimension. Combinations of elements that are organized along the horizontal dimension alone are called strings (a common concept) and combinations of elements organized along the vertical dimension alone are called catenae
Catena (linguistics)
The catena is a unit of syntax and morphology. The unit is closely associated with dependency grammars. It is a more flexible and inclusive unit than the constituent and may therefore be better suited than the constituent to serve as the fundamental unit of syntax and morphosyntax...

 (a novel concept).

Dependency grammars


The following frameworks are dependency-based:
  • Algebraic syntax
    Algebraic syntax
    Recursive categorical syntax, also sometimes called algebraic syntax, is an algebraic theory of syntax developed by Michael Brame as an alternative to transformational-generative grammar.-References:...

    ,
  • Operator Grammar
    Operator Grammar
    Operator Grammar is a mathematical theory of human language that explains how language carries information. This theory is the culmination of the life work of Zellig Harris, with major publications toward the end of the last century...

    ,
  • Functional Generative Description
    Functional Generative Description
    Functional Generative Description is a linguistic framework developed at Charles University in Prague since the 1960s by a team led by Petr Sgall...

    ,
  • Lexicase Grammar,
  • Meaning-Text Theory
    Meaning-Text Theory
    Meaning–text theory is a theoretical linguistic framework, first put forward in Moscow by Aleksandr Žolkovskij and Igor Mel’čuk, for the construction of models of natural language...

    ,
  • Word Grammar
    Word grammar
    Word grammar has been developed by Richard Hudson since the 1980s. It started as a model of syntax, whose most distinctive characteristic is its use of dependency grammar, an approach to syntax in which the sentence's structure is almost entirely contained in the information about individual words,...

    ,
  • Extensible Dependency Grammar

Link grammar
Link grammar
Link grammar is a theory of syntax by Davy Temperley and Daniel Sleator which builds relations between pairs of words, rather than constructing constituents in a tree-like hierarchy. There are two basic parameters: directionality and distance...

 is also based on the dependency relation, but link grammar does not include directionality in the dependencies between words, and thus does not describe head-dependent relationships. Hybrid dependency/constituency grammar uses dependencies between words, but also includes dependencies between phrasal nodes - see for example, the Quranic Arabic Dependency Treebank
Quranic Arabic Corpus
The Quranic Arabic Corpus is an annotated linguistic resource consisting of 77,430 words of . The research project is led by at the University of Leeds, and is part of the Arabic language computing research group within the School of Computing, supervised by...

. The derivation trees of Tree-Adjoining Grammar
Tree-adjoining grammar
Tree-adjoining grammar is a grammar formalism defined by Aravind Joshi. Tree-adjoining grammars are somewhat similar to context-free grammars, but the elementary unit of rewriting is the tree rather than the symbol...

 are dependency-based, although the full trees of TAG are constituency-based, so in this regard, it is not clear whether TAG should be viewed more as a dependency or constituency grammar.

There are major differences between the grammars just listed. In this regard, the dependency relation is compatible with other major tenets of theories of grammar. Thus like constituency grammars, dependency grammars can be mono- or multistratal, representational or derivational, construction- or rule-based.

Implementations

  • Stanford parser A statistical phrase-structure parser which provides a tool to convert the output into a form of dependency graph called "Stanford Dependencies".
  • DeSR A statistical dependency shift/reduce dependency parser.
  • RelEx generates a dependency parse for the English language, by applying graph rewriting
    Graph rewriting
    Graph transformation, or Graph rewriting, concerns the technique of creating a new graph out of an original graph using some automatic machine. It has numerous applications, ranging from software verification to layout algorithms....

     to the output of the link grammar
    Link grammar
    Link grammar is a theory of syntax by Davy Temperley and Daniel Sleator which builds relations between pairs of words, rather than constructing constituents in a tree-like hierarchy. There are two basic parameters: directionality and distance...

     parser. Open source
    Open source
    The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

    license.
  • XDG Development Kit An Integrated Development Environment for Extensible Dependency Grammar (XDG)
  • TULE A linguistic framework that takes a natural language sentence in input (Italian) and returns a full dependency tree describing its syntactic structure.

External links