Pragmatic inferences from the has-relation

The has-relation, restricted to prototypes, is the basis for some of our pragmatic expectations in language use. This can be seen in a switch from indefinite to definite articles. A noun phrase that first brings something into a conversation is usually indefinite (for example, marked by means of an indefinite article, a or an), but on second and subsequent mention of the same thing in the conversation it will be referred to by means of a definite noun phrase (marked by, for example, the definite article the), as in (3.3a, b).

However, if a whole that has a part has been mentioned, then the part can, on first mention, be referred to by means of a definite noun phrase, as illustrated by the use of the in the responses of B and D in (3.4a, b).