Valency (linguistics)

In linguistics, verb valency or valence is the number of arguments controlled by a verbal predicate. It is related, though not identical, to verb transitivity, which counts only object arguments of the verbal predicate. Verb valency, on the other hand, includes all arguments, including the subject of the verb. The linguistic meaning of valence derives from the definition of valency in chemistry. This scientific metaphor is due to Lucien Tesnière, who developed verb valency into a major component of his (what would later become known as) dependency grammar theory of syntax and grammar. The notion of valency first appeared as a comprehensive concept in Tesnière's posthumously published book (1959) Éléments de syntaxe structurale (Elements of structural syntax).

There are several types of valency:

The term valence also refers to the syntactic category of these elements. Verbs show considerable variety in this respect. In the examples above, the arguments are noun phrases (NPs). But arguments can in many cases be other categories, e.g.

Many of these patterns can appear in a form rather different from the ones just shown above. For example, they can also be expressed using the passive voice:

The above examples show some of the most common valence patterns in English, but do not begin to exhaust them. Other linguists have examined the patterns of more than three thousand verbs and placed them in one or more of several dozen groups.

The verb requires all of its arguments in a well-formed sentence, although they can sometimes undergo valency reduction or expansion. For instance, to eat is naturally divalent, as in he eats an apple, but may be reduced to monovalency in he eats. This is called valency reduction. In the southeastern United States, an emphatic trivalent form of eat is in use, as in I'll eat myself some supper. Verbs that are usually monovalent, like sleep, cannot take a direct object. However, there are cases where the valency of such verbs can be expanded, for instance in He sleeps the sleep of death. This is called valency expansion. Verb valence can also be described in terms of syntactic versus semantic criteria. The syntactic valency of a verb refers to the number of dependent arguments that the verb can have, while semantic valence describes the thematic relations associated with a verb.

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