5.3.1 Relative Clauses

Relative clauses.

Consider these two English NPs:

This NP contains a relative clause where the relative pronoun is the direct object. Next, an NP with a relative pronoun in subject position:

What is the syntax of such NPs? That is, how do we build them? We are going to start off by giving a fairly traditional explanation in terms of movement , gap s, extraction , and so on. As we'll soon see, it's pretty easy to think of these ideas in terms of features, and to implement them using DCGs.

The Traditional Explanation

The traditional explanation basically goes like this. We start from the following sentence: ``Harry likes the witch'' Now we can think of the NP with the object relative clause as follows.

That is, we can think of it as being formed from the original sentence by (1) extracting the NP ``the witch'' from its original position, thereby leaving behind an empty NP, or an NP-gap, and (2) moving it to the front, and (3) inserting relative pronoun ``who'' between it and the gap-containing sentence.

What about the subject relative clause example? We can think of this as follows:

That is, we have (1) extracted the NP ``Harry'' from the subject position, leaving behind an NP-gap, (2) moved it to the front, and (3) placed the relative pronoun ``who'' between it and the gap-containing sentence.

But why are relative clause constructions an example of unbounded dependencies? The word `dependency' indicates that the moved NP is linked, or depends on, its original position. The word `unbounded' is there because this ``extracting and moving'' operation can take place across arbitrary amounts of material. For example, from ``A witch who Harry likes, likes a witch.'' we can form

And we can iterate such constructions indefinitely --- albeit, producing some pretty hard to understand sentences. For example, from: `` A witch who a witch who Harry likes, likes a witch.'' we can form

In what follows we shall see that, by using features, we can give a nice declarative account of the basic facts of English relative clauses. Indeed, we won't even have to think in terms of movement. We'll just need to think about what information is missing from where, and how to keep track of it.