Dependency grammar

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Dependency grammar (DG) is a class of syntactic theories developed by Lucien Tesnière. It is distinct from phrase structure grammars, as it lacks phrasal nodes. Structure is determined by the relation between a word (a head) and its dependents. Dependency grammars are not defined by a specific word order, and are thus well suited to languages with freer word order, such as Czech.

Algebraic syntax and Extensible Dependency Grammar are types of dependency grammar. Link grammar is similar to dependency grammar, but link grammar includes directionality in the relations between words, as well as lacking a head-dependent relationship.

Operator Grammar differs from other dependency grammars in that it is also a theory of semantics (information). This theory posits a large collection of reductions (small transformations) that map dependency structures into compact, variant forms. It also reverses the direction of dependency, by having operators (e.g. verbs) depend on their arguments.