The range of representable concepts

A wide range of entities can be represented by this knowledge scheme. For instance, ``The tall boy is walking to the store'' is a description of an action: walking. A boy is doing the walking; his destination is the object known as a store. In this example, the boy is known to be tall, which is part of the state description for that boy. For this example to be fully represented, the concepts of tall, boy, walk, and store need to exist in the knowledge base; the way in which they become related represents the meaning of the sentence.

In this example action, all of the entities exist in the physical world. This is not always the case, of course. Consider ``Yesterday, the angry girl thought of a plan to get revenge.'' Thinking is an action, but not physical; instead, it is a mental action. The girl is angry; this is part of her emotional state description. The event occurred yesterday, which places it in a specific time span. Revenge is somewhat problematic; it is sort of emotional but probably involves some physical aspect. The best way to describe it is as a social object--revenge only makes sense if you consider it in terms of multiple agents. As with the first example, a number of concepts need to exist for the meaning of the sentence to be represented: girl, angry, yesterday, think, plan, and revenge.