5.2.7 From Lambda-Expressions to an Underspecified Description

An example of how to get to an underspecified description.

Let us look at our example once more and go through step by step how we have constructed the constraint graph describing our two -expressions. We had to take four steps:

1. We wrote down all (two) readings of the sentence, as -expressions:

   1.

   2.

2. We converted the readings into -structures:

   

3. We identified the common material in both -structures. Generally, each block of common material must be contiguous (linked internally with only solid edges). It may be a complete subtree (like the purple part), or it may be just a tree fragment (like the other two parts).

   

4. We built an underspecified description that expresses what material the readings contain, and what structural constraints we must obey when putting that material together.

   

What we have just done, namely going from a natural language sentence via all its readings to an underspecified description, does not correspond to any part of our system architecture. We started off from fully specified -structures. But once we hold all -structures for a sentence in our hands, there is of course no point in constructing an underspecified description any more. Yet we hope that our discussion has given you a better idea of how this whole underspecification business works. Our explanations should enable you to solve the following exercise.