11.2.6 Discourse Structure and Accessibility

Some more examples that show that DRS structure plays a central role for determining the possibility of anaphoric links.

Let's look at some more examples that show that DRS structure plays a central role for determining the possibility of anaphoric links between pronouns and their potential antecedents. Indefinite noun phrases normally introduce their discourse referents ``locally'' and hence are not accessible from outside a negation or implication.

First consider the following example:

``John has a valuable watch. He left it in his apartment.''

Here we first construct a DRS for the first sentence, creating two discourse referents (x for John, and y for his watch). On interpreting the second sentence, the DRS gets extended and the pronouns ``he'' and ``it'' get resolved to John and his watch, respectively.

If we change this example slightly, using a conditional in the first sentence, we will get the following DRSs:

``If John has a valuable watch, he will take care of it.''

As we can see from this DRS, an ``if'' connector introduces an implicational condition. Note that the indefinite noun phrase \nl{a valuable watch} is introduced in an embedded sentence (Further note that the DRS-conditions for the proper name \nl{John} are introduced in the main DRS. In a few moments we will explain why proper names behave this way.)

If we now attempt to continue the discourse with a pronoun referring to this watch, we fail to do so:

``If John has a valuable watch, he will take care of it. * He left it in his apartment.''

The reason why DRT correctly predicts this impossible anaphoric link runs as follows: The discourse referent v for the pronoun ``it'' cannot be linked to y, because the DRS in which v is introduced subordinates the DRS in which v is declared. Hence, the y is not accessible for v, and DRT correctly predicts this impossibility.

Now consider another pair of examples, this time involving negation.

``Mary ordered a milk shake. John tasted it.''

In this example an anaphoric link between ``it'' and \nl{a milk shake} is allowed since the discourse referent y (denoting \nl{a milk shake}) is accessible for discourse referent v, introduced by the pronoun. In the following example, where we introduced negation, an anaphoric link is blocked, because here y is not accessible for v:

``Mary did not order a milk shake. *John tasted it.''

Similar observations can be made with respect to disjunction. The reader is asked to attempt the following exercise to find out what DRT predicts on anaphoric links to antecedents in disjunctive clauses.

Exercise 11.2

Analyse the following examples and translate them into DRSs. Are anaphoric links between the pronoun ``it'' and ``an apple'' permitted?

  1. ``Bill eats an apple. It is delicious.''

  2. Bill eats an apple or a pear. It is delicious.

What do you think about this example?

  • Bill eats an apple or a pear. The apple is delicious.


Aljoscha Burchardt, Stephan Walter, Alexander Koller, Michael Kohlhase, Patrick Blackburn and Johan Bos
Version 1.2.5 (20030212)