Concept
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). Languages typically construct phrases with a head word (or nucleus) and zero or more dependents (modifiers). The following phrases show the phrase heads in bold. Examples of left-branching phrases (= head-final phrases): the house - Noun phrase (NP) very happy - Adjective phrase (AP) too slowly - Adverb phrase (AdvP) Examples of right-branching phrases (= head-initial phrases): laugh loudly - Verb phrase (VP) with luck - Prepositional phrase (PP) that it happened - Subordinator phrase (SP = subordinate clause) Examples of phrases that contain both left- and right-branching (= head-medial phrases): the house there - Noun phrase (NP) very happy with it - Adjective phrase (AP) only laugh loudly - Verb phrase (VP) Concerning phrases such as the house and the house there, this article assumes the traditional NP analysis, meaning that the noun is deemed to be head over the determiner. On a DP-analysis (determiner phrase), the phrase the house would be right-branching instead of left-branching. Left- and right-branching structures are illustrated with the trees that follow. Each example appears twice, once according to a constituency-based analysis associated with a phrase structure grammar and once according to a dependency-based analysis associated with a dependency grammar.