Introduction to Prolog (Part 1)

History of Prolog

• Prolog was developed at the University of Marseilles, France by Alain Colmerauer in the early 1970s as a convenient tool for PROgramming in LOGic.

• In 1983 Japan chose Prolog as the main language for 5th generation computers.

• Turbo Prolog was the first implementation of Prolog for IBM PC that came out in 1986.

• Visual Prolog is developed by PDC in Denmark.

What Can Prolog be Used For?

• Expert Systems.
• Artificial Intelligent Systems.
• Translate languages, either natural human languages or from one programming language to another.
• Construct Natural Language interfaces to existing software.
• Control and monitoring of industrial processes.
• Theorem proving software in which deductive reasoning capabilities are used.
• Development of Relational Databases.
• Produce prototypes for virtually any application program.

In what Areas Prolog is Distinctively Better?

• Prolog is a Descriptive Language.

• Prolog Uses Facts and Rules.

• Prolog can make Deductions.

• Pattern Matching ability.

• Execution of Prolog Programs is Controlled automatically.

• Prolog is very User-friendly and has a short and simple syntax.

• Efficiency of Application Programs is almost as good as for C++ programs.

Glossary of Terms

• Atom: A relation possibly involving objects or variables.
• Domain: Specifies the types of values the objects may take in relation.
• Clause: A fact or rule for a particular predicate, followed by a period.
• Fact: . Facts declare things that are always true. It is a relation between objects. In the fact;
• likes(john, mary)
• likes is the name of the relation and john and mary are objects.

• Rule: Rules declare things that are true depending on some conditions. It is a relationship between a fact and a list of sub-goals which must be satisfied for that fact to be true.
• Predicate: Every Prolog fact or rule belongs to some predicate, which specifies the name of the relation involved and the types of objects involved in the relation.
• Backtracking: The mechanism built into Prolog whereby, when evaluation of a given sub-goal is complete, Prolog returns to the previous sub-goal and tries to satisfy it in a different way.