17.1.1 Verifiability

Let us begin by considering the following simple question:

(17.1) Does Maharani serve vegetarian food?

This example illustrates the most basic requirement for a meaning representation: it must be possible to use the representation to determine the relationship between the meaning of a sentence and the world as we know it. In other words, we need to be able to determine the truth of our representations. The most straightforward way to implement this notion is to make it possible for a system to compare, or match, the representation of the meaning of an input against the representations in its knowledge base, its store of information about its world.

In this example, let us assume that the meaning of this question contains, as a component, the meaning underlying the proposition Maharani serves vegetarian food. For now, we will simply gloss this representation as:

Serves(Maharani, VegetarianFood)

It is this representation of the input that will be matched against the knowledge base of facts about a set of restaurants. If the system finds a representation matching the input proposition in its knowledge base, it can return an affirmative answer. Otherwise, it must either say No, if its knowledge of local restaurants is complete, or say that it does not know if there is reason to believe that its knowledge is incomplete.

This notion is known as $ \underline{\text{verifiability}} $, and concerns a system's ability to compare the state of affairs described by a representation to the state of affairs in some world as modeled in a knowledge base.