Linguistic Valency in Grammar

In linguistics, valency is the number and type of connections that syntactic elements can form with one other in a sentence. Also known as complementation. The term valency is derived from the field of chemistry, and as in chemistry, notes David Crystal, "a given element may have different valencies in different contexts."

Examples and Observations:

"Like atoms, words tend not to occur in isolation but to combine with other words to form larger units: the number and type of other elements with which a word can occur is a very important part of its grammar. As with atoms, the ability of words to combine in this way with other words is called valency.

"Valency—or complementation, as it is often called—is an important area of the description of English, one which is on the boundaries of lexis and grammar, and as such has been dealt with in grammars and dictionaries of English."
(Thomas Herbst, David Heath, Ian F. Roe, and Dieter Götz, A Valency Dictionary of English: A Corpus-Based Analysis of the Complementation Patterns of English Verbs, Nouns, ​and Adjectives. Mouton de Gruyter, 2004)​

Valency Grammar

"A valency grammar ​presents a model of a sentence containing a fundamental element (typically, the verb) and a number of dependent elements (variously referred to as arguments, expressions, complements, or valents) whose number and type is determined by the valency attributed to the verb. For example, the valency of vanish includes only the subject element (it has a valency of 1, monovalent, or monadic), whereas that of scrutinize includes both subject and direct object (a valency of 2, bivalent, or dyadic). Verbs which take more than two complements are polyvalent, or polyadic. A verb which takes no complements at all (such as rain) is said to have zero valency (be avalent). Valency deals not only with the number of valents with which a verb is combined to produce a well-formed sentence nucleus but also with the classification of sets of valents which may be combined with different verbs. For example, give and put usually have a valency of 3 (trivalent), but the valents governed by the former (subject, direct object, and indirect object) are different from those governed by the latter (subject, direct object, and locative adverbial). Verbs which differ in this way are said to be associated with different valency sets." (David Crystal, A Dictionary of Linguistics and Phonetics, 6th ed. Blackwell, 2008)

Valency Patterns for Verbs

"The main verb in a clause determines the other elements that are required in that clause. The pattern of the clause elements is called the valency pattern for the verb. The patterns are differentiated by the required clause elements that follow the verb within the clause (e.g. direct object, indirect object, subject predicative). All valency patterns include a subject, and optional adverbials can always be added.

There are five major valency patterns:

A. Intransitive
Pattern: subject + verb (S + V). Intransitive verbs occur with no obligatory element following the verb. . . .
B. Monotransitive
Pattern: subject + verb + direct object (S + V + DO). Monotransitive verbs occur with a single direct object. . . .
C. Ditransitive
Pattern: subject + verb + indirect object + direct object (S + V + IO + DO). Ditransitive verbs occur with two object phrases--an indirect object and a direct object. . . .
D. Complex transitive
Patterns: subject + verb + direct object + object predicative (S + V + DO + OP) or subject + verb + direct object + obligatory adverbial (S + V + DO + A). Complex transitive verbs occur with a direct object (a noun phrase) which is followed by either (1) an object predicative (a noun phrase or adjective), or (2) an obligatory adverbial. . . .
E. Copular
Patterns: subject + verb + subject predicative (S + V + SP) or subject + verb + obligatory adverbial (S + V + A). Copular verbs are followed by (1) a subject predicative (a noun, adjective, adverb, or prepositional phrase) or (2) by an obligatory adverbial. . . ."

(Douglas Biber et al. Longman Student Grammar of Spoken and Written English. Pearson, 2002)

Valency and Complementation

"The term 'valency' (or 'valence') is sometimes used, instead of complementation, for the way in which a verb determines the kinds and number of elements that can accompany it in the clause. Valency, however, includes the subject of the clause, which is excluded (unless extraposed) from complementation."
(Randolph Quirk, Sidney Greenbaum, Geoffrey Leech, and Jan Svartvik, A Grammar of Contemporary English. Longman, 1985)