Parse tree in the context of "Context-free grammar"

Generative grammar is a research tradition in linguistics that aims to explain the cognitive basis of language by formulating and testing explicit models of humans' subconscious grammatical knowledge. Generative linguists tend to share certain working assumptions such as the competence–performance distinction and the notion that some domain-specific aspects of grammar are partly innate in humans. These assumptions are often rejected in non-generative approaches such as usage-based models of language. Generative linguistics includes work in core areas such as syntax, semantics, phonology, psycholinguistics, and language acquisition, with additional extensions to topics including biolinguistics and music cognition.

Generative grammar began in the late 1950s with the work of Noam Chomsky, having roots in earlier approaches such as structural linguistics. The earliest version of Chomsky's model was called Transformational grammar, with subsequent iterations known as Government and binding theory and the Minimalist program. Other present-day generative models include Optimality theory, Categorial grammar, and Tree-adjoining grammar.

Syntactic ambiguity, also known as structural ambiguity, amphiboly, or amphibology, is characterized by the potential for a sentence to yield multiple interpretations due to its ambiguous syntax. This form of ambiguity is not derived from the varied meanings of individual words but rather from the relationships among words and clauses within a sentence, concealing interpretations beneath the word order. Consequently, a sentence presents as syntactically ambiguous when it permits reasonable derivation of several possible grammatical structures by an observer.

In jurisprudence, the interpretation of syntactically ambiguous phrases in statutory texts or contracts may be done by courts. Occasionally, claims based on highly improbable interpretations of such ambiguities are dismissed as being frivolous litigation and without merit. The term parse forest refers to the collection of all possible syntactic structures, known as parse trees, that can represent the ambiguous sentence's meanings. The task of clarifying which meaning is actually intended from among the possibilities is known as syntactic disambiguation.

In linguistics, branching refers to the shape of the parse trees that represent the structure of sentences. Assuming that the language is being written or transcribed from left to right, parse trees that grow down and to the right are right-branching, and parse trees that grow down and to the left are left-branching. The direction of branching reflects the position of heads in phrases, and in this regard, right-branching structures are head-initial, whereas left-branching structures are head-final. English has both right-branching (head-initial) and left-branching (head-final) structures, although it is more right-branching than left-branching. Some languages such as Japanese and Turkish are almost fully left-branching (head-final). Some languages are mostly right-branching (head-initial).