Editing Sentence diagram (section)

==Constituency and dependency==
Reed–Kellogg diagrams reflect, to some degree, concepts underlying modern parse trees. Those concepts are the constituency relation of [[phrase structure grammar]]s and the dependency relation of [[dependency grammar]]s. These two relations are illustrated here adjacent to each other for comparison, where D means Determiner, N means Noun, NP means Noun Phrase, S means Sentence, V means Verb, VP means Verb Phrase and IP means Inflectional Phrase.

[[File:Sentence-diagram3.svg|Constituency and dependency]]
[[File:Xbarst1.svg|thumb|X-bar theory graph of the sentence "He studies linguistics at the university."]]

Constituency is a one-to-one-or-more relation; every word in the sentence corresponds to one or more nodes in the tree diagram. Dependency, in contrast, is a one-to-one relation; every word in the sentence corresponds to exactly one node in the tree diagram. Both parse trees employ the convention where the category acronyms (e.g. N, NP, V, VP) are used as the labels on the nodes in the tree. The one-to-one-or-more constituency relation is capable of increasing the amount of sentence structure to the upper limits of what is possible. The result can be very "tall" trees, such as those associated with [[X-bar theory]]. Both constituency-based and dependency-based theories of grammar have established traditions.<ref name="Chomsky 1957">{{cite book |last=Chomsky |first=Noam |author-link=Noam Chomsky |title=[[Syntactic Structures]] |date=1957 |publisher=[[De Gruyter|Mouton de Gruyter]] |location=The Hague/Paris}}</ref><ref name="Tesniere 1959">{{cite book |last=Tesnière |first=Lucien |author-link=Lucien Tesnière |title=Éléments de syntaxe structurale |date=1959 |publisher=Klincksieck |location=Paris |language=fr}}</ref>

Reed–Kellogg diagrams employ both of these modern tree generating relations. The constituency relation is present in the Reed–Kellogg diagrams insofar as subject, verb, object, and/or predicate are placed equi-level on the horizontal base line of the sentence and divided by a vertical or slanted line. In a Reed–Kellogg diagram, the vertical dividing line that crosses the base line corresponds to the binary division in the constituency-based tree (S → NP + VP), and the second vertical dividing line that does not cross the baseline (between verb and object) corresponds to the binary division of VP into verb and direct object (VP → V + NP). Thus the vertical and slanting lines that cross or rest on the baseline correspond to the constituency relation. The dependency relation, in contrast, is present insofar as modifiers dangle off of or appear below the words that they modify.