Subcategorization

Subcategorization in linguistics refers to the specification by a lexical item, particularly a verb, of the syntactic contexts in which it can occur. A subcategorization frame, also called an argument structure or valency frame, lists the number and type of arguments a word requires or permits and how they are realized in a sentence. For example, the verb sleep has an intransitive frame (no object); eat selects for a direct object NP (transitive); give selects for two NP objects (a ditransitive frame: NP indirect object and NP direct object). Some verbs require a prepositional complement, as in depend on someone (V PP).

Subcategorization frames are encoded in lexical entries in dictionaries and lexical databases, and they guide grammaticality judgments, parsing, and generation. They are language-specific and reflect valency patterns of a language; different languages may realize the same frame with different morpho-syntactic markers (case, prepositions) or different word orders. Subcategorization interacts with movement and passive constructions: passivization often reduces the number of core arguments, changing the frame.

In linguistic theory, subcategorization is linked to valency theory and theta roles; it helps distinguish semantic core participants from syntactic structure. Large lexical resources, such as VerbNet and FrameNet, annotate verbs with their subcategorization frames and associated semantic roles, supporting both theoretical analysis and natural language processing.