Subcategorisation

The lexicon contains more syntactic information than merely the lexical category of each word. If it did not, speakers of English would be unable to make the following grammaticality distinctions

The boy found the ball.

• The boy found quickly.
• The boy found in the house.

The boy found the ball in the house.

The verb find is a transitive verb. A transitive verb must be followed by a noun phrase, its direct object. This additional specification is called subcategorisation and is also included in the lexical enty of each word.

Most words in the lexicon are subcategorised for certain contexts. Subcategorisation accounts for the ungrammaticality of  :

• John put the milk.
• Sylvia slept the baby.

The verb put occurs with both a noun phrase and a prepositional phrase, as in John put the milk in the refrigerator. Sleep is an intransitive verb, so it cannot be followed by an NP. This informtion is included as the subcategorisation of each word.

Other categories besides verbs are subcategorised. For example, within the NP, if the determiner is lacking, only a plural noun (or proper name ) may be inserted; and if the determiner is a, only a singular noun may be iserted. This accounts for the following  :

Puppies love warm milk.

• Puppy loves warm milk.

A puppy loves warm milk.

• A puppies love warm milk.

Subcategorisation within the NP affects individual nouns. Belief is subcategorised for both a PP at an S, as shown by the following ttwo examples  :

the belief in freedom of speech
the belief that freedom of speech is a basec right

The noun sympathy, however, is subcategorised for a PP, but not an S :

their sympathy for the victims

• their sympathy that the victims are so poor

Knowledge about subcategorisation may be accounted for in the lexicon as follows  :

A fragment of the lexicon
put, V, ________ NP PP

find, V, ________ NP

sleep, V, ________

belief, N, ________ (PP), _____ (S)

sympathy, N, ________ (PP)


Comments
put, is a verb and must be followed by both an NP and a PP within the verb phrase.

find, is a verb and must be followed by an NP within the verb phrase.

sleep, is a verb abd must not be followed by an NP within the verb phrase

belief, is a noun and may be followed by either a PP or am S within the noun phrase

sympathy, is a noun and may be followed by a PP within the noun phrase

Just as lexical insertion ensures that verbs are inserted under a V node in a tree, nouns under an N node, and so on, it also ensures that, for example, intransitive verbs such as sleep can only appear in trees in which the VP has no direct object. Similarly, put could only occur in trees where it would be followed by an NP and a PP within tha verb phrase, and so on.