A Procedure for Thinking - Thinking as Computation - page 29

Example 2

Establish the query gina is female .

1. Look for gina is female in the KB. Nothing found.

2. Look for If . . . then gina is female in the KB. Nothing found.

Return failure for gina is female .

Example 3

Establish the query george is a father of sue .
1. Look for george is a father of sue in the KB. Nothing found.

2. Look for If . . . then george is a father of sue in the KB.

Found: If X is a child of Y and Y is male then Y is a father of X.
This matches for Y=george and X=sue .

3. Work on the two if-parts of this matching conditional:

(Note in figure 2.2 that the two parts are worked on from left to right.)

Establish the query sue is a child of george .
(This is the query X is a child of Y with X=sue and Y=george .)
1. Look for sue is a child of george in the KB. Found.

Return success for sue is a child of george .
Establish the query george is male .
(This is the query Y is male with Y=george .)
1.

Look for george is male in the KB. Found.

Return success for george is male .

Since both parts were successful, return success for the original query
george is a father of sue .

Example 4

Establish the query jane is of opposite sex from george .

1. Look for jane is of opposite sex from george in the KB. Nothing found.

2. Look for If . . . then jane is of opposite sex from george in the KB.

Found: If X is male and Y is female then X is of opposite sex from Y.
This matches for X=jane and Y=george .