Knowledge-Based Systems

2.11 appliCations 43

When the knowledge-based system makes a decision, it needs to justify it—

especially when the system is not being told explicitly how to perform the

given task. For instance, suppose an information retrieval program “knows”

only that “animals breathe oxygen” and that “all dogs are animals”; then the

system may answer perfectly questions like:

Do animals breathe oxygen? Yes.

Are all dogs animals? Yes.

If we ask, “Do dogs breathe oxygen?” then the program must use reason

to answer the query. In problems of any complexity, the ability to do this be-

comes increasingly important. The system must be able to deduce and verify

a multitude of new facts beyond those it has been told explicitly.

2.10 EXPLANATION

Presenting the ...