Тіл біліміндегі эндоцентрлік және экзоцентрлік құрылымдардың айырмашылығы

Distinction between phrases that have a primary word ("head") and that don't

In theoretical linguistics, a distinction is made between endocentric and exocentric constructions. A grammatical construction (for instance, a phrase or compound) is said to be endocentric if it fulfils the same linguistic function as one of its parts, and exocentric if it does not. The distinction reaches back at least to Bloomfield's work of the 1930s, who based it on terms by Pāṇini and Patañjali in Sanskrit grammar. Such a distinction is possible only in phrase structure grammars (constituency grammars), since in dependency grammars all constructions are necessarily endocentric.

The endo vs. exocentric distinction is possible in phrase structure grammars (= constituency grammars), since they are constituency based. The distinction is hardly present in dependency grammars, since they are dependency based. In other words, dependency based structures are necessarily endocentric, i. e. they are necessarily headed structures. Dependency grammars by definition were much less capable of acknowledging the types of divisions that constituency enables. Acknowledging exocentric structure necessitates that one posit more nodes in the syntactic (or morphological) structure than one has actual words or morphs in the phrase or sentence at hand. What this means is that a significant tradition in the study of syntax and grammar has been incapable from the start of acknowledging the endo vs. exocentric distinction, a fact that has generated confusion about what should count as an endo or exocentric structure.

Theories of syntax (and morphology) represent endocentric and exocentric structures using tree diagrams and specific labeling conventions. The distinction is illustrated here using the following trees. The first three trees show the distinction in a constituency based grammar, and the second two trees show the same structures in a dependency based grammar:

The upper two trees on the left are endocentric since each time, one of the parts, i. e. the head, projects its category status up to the mother node. The upper tree on the right, in contrast, is exocentric, because neither of the parts projects its category status up to the mother node; Z is a category distinct from X or Y. The two dependency trees show the manner in which dependency based structures are inherently endocentric. Since the number of nodes in the tree structure is necessarily equal to the number of elements (e. g. words) in the string, there is no way to assign the whole (i. e. XY) a category status that is distinct from both X and Y. Traditional phrase structure trees are mostly endocentric, although the initial binary division of the clause is exocentric (S → NP VP), as mentioned above, e. g.

This tree structure contains four divisions, whereby only one of these division is exocentric (the highest one). The other three divisions are endocentric because the mother node has the same basic category status as one of its daughters. The one exocentric division disappears in the corresponding dependency tree:

Dependency positions the finite verb as the root of the entire tree, which means the initial exocentric division is impossible. This tree is entirely endocentric.