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Part 1 - Facts, Rules and Queries

Video

Programming In Prolog Part 1 - Facts, Rules and Queries

Textual Facts:

1. Jonny is fat
2. The dog is brown
3. Suzie likes Bobby

Convert to predicate logic

Predicates:

1. fat
2. brown
3. likes

Facts

  • fat(jonny). <- every expression or fact is ended with a dot
  • brown(dog).
  • likes(suzie, Bobby). <- The number of arguments is called Arity

Rules:

They extend the facts and their relationship. Infer facts from other facts. If we have the following setup:

likes(ryan, brittney).
likes(brittney, ryan).
likes(dan, josh).

We can ask do they date ? So we are going to create a rule.

:- - if only if

dating(X, Y) :-
	likes(X,Y),
	likes(Y, X).

Table of operators:

and | ,
---------
if  | :-
---------
or  | ;
---------
not | not

Queries

Are dan and sally dating ?

likes(dan, sally).

Are josh and brittney friends ?

friendship(josh, brittney).

Workfiles