ai-prolog4

ai-prolog4 - AI: Prolog Review of Prolog Rules and Facts...

This preview shows pages 1–6. Sign up to view the full content.

1 AI: Prolog Review of Prolog Rules and Facts Prolog Syntax Matching

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Prolog Basics - Revisited Prolog program consists of facts and rules. animal(lion). animal(sparrow). hasfeathers(sparrow). bird(X) :- animal(X), hasfeathers(X). “Run” by asking questions or queries. Or (using logic terminology) by setting a goal for Prolog to try to prove: To find out if something is true: ?- bird(sparrow). yes Or to find a value of a variable that makes it true: ?- bird(What). What = sparrow
3 Prolog Execution A Prolog rule consists of a head and a body. a(X) :- b(X), c(X). When Prolog tries to answer a query (prove a goal) it does so by trying to match the goal to the head of the rule. This might result in some variables getting bound. ?- a(thing). a(thing) MATCHES a(X) so X is bound to the value “thing”. Now it tries to prove the goals in the body of the rule, using these variable bindings:: b(thing) and c(thing) head body

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Example likes(mary, X) :- strong(X), handsome(X). strong(Y) :- tall(Y). tall(john). handsome(john). ?- likes(mary, john). MATCHES likes(mary, john) to head of rule 1, with X=john. Sets strong(john), handsome(john) as new goals. Tries to prove strong(john). MATCHES head of rule 2. Y=john. Tries to prove tall(john). MATCHES a fact. So proved. Tries to prove handsome(john). MATCHES a fact, So proved.
5 Example: Using Prolog Trace | ?- likes(mary, john). 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/20/2011 for the course CS 6810 taught by Professor Hecker during the Spring '10 term at CSU East Bay.

Page1 / 19

ai-prolog4 - AI: Prolog Review of Prolog Rules and Facts...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online