Day 1

Key Points

Logical
Declarative
Function (a.k.a. Clause)
Function Body (a.k.a Predicate)

Key Terms

Facts
Rules
Queries
Knowledge Base

The Interpreter

                        
    gprolog

Loading Files

                        
    consult('lists.pl').

    reconsult('lists.pl').

    ['lists']

    ['file1.pl', 'file2.pl', 'file3.pl'].

Atoms

A symbol is called an atom and begins with lowercase

Variable

Begins with uppercase

Knowledge Base

                        
likes(wallace, cheese).
likes(grommit, cheese).
likes(wendolene, sheep).

Rules

                        
friend(X, Y) :- \+(X = Y), likes(X, Z), likes(Y, Z).

:- To the right is a subgoal
\+ To the right is a logical negation
friend/2 with 3 Subgoals

Using Variables

                        
food_type(velveeta, cheese).
food_type(ritz, cracker).
food_type(spam, meat).
food_type(sausage, meat).
food_type(jolt, soda).
food_type(twinkie, dessert).

flavor(sweet, dessert).
flavor(savory, meat).
flavor(savory, cheese).
flavor(sweet, soda).

food_flavor(X, Y) :- food_type(X, Z), flavor(Y, Z).

                        
    food_type(What, meat).

Using Variables

                        
    food_type(What, meat).

    food_flavor(sausage, sweet).

    flavor(sweet, What).

Where's the program?

Just describe your problem, let Prolog solve it!

Unification

= is the Prolog symbol for unification

                        
cat(lion).
cat(tiger).

dorothy(X, Y, Z) :- X = lion, Y = tiger, Z = bear.
twin_cats(X, Y)  :- cat(X), cat(Y).

                        
    dorothy(lion, tiger, bear).

    dorothy(One, Two, Three).

    twin_cats(One, Two)

Unification

                        
    twin_cats(One, Two)

How does this actually work?

Assignment

Start the Assignment

Read Day 2

Resources

http://www.lix.polytechnique.fr/~liberti/public/computing/prog/prolog/prolog-tutorial.html
http://www.cpp.edu/~jrfisher/www/prolog_tutorial/contents.html