xdanielsb / prolog

Prolog

Prolog is a logical and declarative language, the name comes from PROgraming LOGic

• Fourth generation Programing language

Applications

• Natural Language Understanding
• Expert systems
• Machine Learning
• Specification Language

How to

 $ swipl
 ?- [p01_relationsClass].  # this will load the program
 ...
 # execute your queries over that knowledge

Theory

Relations

It is a property that assign a true value

• Elon Musk is a human -> human(elonMusk)
• Earth is round -> round(earth)

In prolog a fact is an explicity relation

Rules

It is a restriction given to a relation, help to find a fact even is not explicity and stated

• Juan (X) is my (Y) grandfather if Juan is the father of my father(Z) or the father of my mother(Z)
• grandfather(X, Y):- (father(Z, Y), father(Z, X));(father(Z, Y),mother(Z, X))

Syntax of prolog

• names of relations must be stated in lower case
• the relation name appears as the first term #signature of relation
• objects appears in the relation separated by commas
• Must be written a period at the end of the fact or rule
• objects can also begin with digits
• string also can be written enclosed in quotes
• variables names must start with a capital letter or an underscore
• :- means if , also called the neck symbol
• , (comma) is called conjuction (and) symbol
• ; (semicolon) is called disjunction (or) symbol

List

Simple data structure, can be written as a Prolog atom as

L = []