Syntactic subcategories, subcategorisation restrictions, subcategorisation frames

A syntactic category is generally defined with respect to a cluster of properties. A syntactic subcategory is a distinguished within a given category in terms of its characteristic syntagmatic relations with other categories.

Traditional terms such as `intransitive', `transitive', `ditransitive', `double transitive' express subcategories of the category VERB. More explicitly, these terms mean that a verb is syntagmatically linked with certain other categories such as NOUN PHRASE, PREPOSITIONAL PHRASE.

The kind of syntagmatic relation involved in defining syntactic subcategories is the government relation:

1. The verb is HEAD.
2. Other (complex) categories such as NOUN PHRASE, PREPOSITINAL PHRASE, SENTENCE (FINITE or NONFINITE CLAUSE) are COMPLEMENTS.
3. The number of COMPLEMENTS is called the valency or arity of the verb.
4. The sequence of categories which enter into characteristic syntagmatic relations with a given verb is its subcategorisation frame (the conventional term) or SUBCAT LIST (HPSG -- Head-Driven Phrase Structure Grammar).
5. Traditionally, the SUBJECT is not included in the subcategorisation frame, however for transparency it will be included here.
6. Examples of subcategorisation frames:

   open The door opened. John opened the door. This key opened the door. The door opened with this key. John opened the door with this key. * John opened. * This key opened. * John opened with this key.

The subcategorisation frame is still insufficiently finely grained to distinguish between the two cases of , however. For this, other means have been developed. To distinguish it from the more finely grained varieties of subcategorisation, this variety is called strict subcategorisation.

Reference: The earliest systematic modern treatment of (strict) subcategorisation is in:
Chomsky, N. (1965). Aspects of the Theory of Syntax. Cambridgd, Mass.: MIT Press.