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What is Prolog Programming Language: An Overview/ai-insights/what-is-prolog-programming-language-an-overview

What is Prolog Programming Language: An Overview

March 04, 2024

What is Prolog Programming Language: An Overview

If we analyze the current world of technology, there are several kinds of programming languages that have been empowering professionals to bring intelligent systems to life. Python and Java are the two most dominating programming languages in the world currently that are used in data science, artificial intelligence, cybersecurity, software development, and all kinds of technical industries. But Prolog stands out from all other programming languages as a unique tool specially designed for AI applications and AI programming.

In this article, let us understand the essence of Prolog, and explore its core concepts, applications, and its potential value for AI professionals.

What is Prolog Programming?

Before we learn in detail about “Prolog-the language”, let us first see what prolog programming is. Prolog refers to the different kinds of programming languages that are based on logic and reasoning. While traditional languages focus on solving problems step-by-step, prolog programming languages declaratively state the problems and their relationship and leave the solution process to the interpreter. Thus, making it powerful for tasks that involve symbolic reasoning, knowledge representation, and artificial intelligence (AI).

What is Prolog?

Prolog is one of the most popular logic programming languages that is highly suitable for artificial intelligence and logic. It was developed in the 1970s and initially intended to build intelligent systems that can do reasoning and problem-solving like humans. Now, though its use in mainstream AI has reduced, it still remains a valuable tool in many specific areas such as expert systems and natural language processing.

Core concepts of Prolog

Prolog programming for artificial intelligence is built upon four fundamental concepts; facts, rules, variables, and queries.

  • Facts

    They are the statements that are assumed to be true while working with programming language. In prolog, facts are the basic building blocks of knowledge and represent simple statements about the world that are similar to sentences in natural language.


    parent(john, mary).

    age(mary, 25).

    city(john, london).

  • Rules

    They express relationships between facts and help with reasoning and deducting. Rules consist of a head, and a body, where the head represents the conclusion to be drawn and the body refers to the conditions that need to be met for the conclusion to be true.


    mortal(X):- human(X). % Rule: If X is human, then X is mortal

    older(X, Y):- parent(X, Y). % Rule: If X is the parent of Y, then X is older than Y

  • Variables

    They are the placeholders for unknown values in the facts and rules. Variables help Prolog to perform unification i.e. a process of matching variables with specific values to satisfy a rule.

    Example: likes(X, music) :- genre(X, Pop). % Rule: Someone likes music if their genre is Pop

  • Queries

    It is used to ask the interpreter to solve problems based on the rules and facts in the program. They are written using the same syntax as facts but followed by a question mark.

Applications of Prolog

Prolog has unique capabilities that make it suitable for various AI applications, especially in:

  • Expert systems: Prolog can represent knowledge and reason logically making it ideal for building expert systems that can capture and apply the knowledge of human experts in specific domains.
  • Natural Language Processing: Prologs are used to develop systems capable of understanding and processing human languages and help machines with translation and sentiment analysis
  • Logic Programming and Theorem Proving: Having a strong foundation in logic, a prolog is a valuable tool to formalize and reason logical systems. It helps mathematicians and computer scientists to prove theorems and explore logical relationships.
  • Education: Learning Prolog is good for developing critical thinking problem-solving, and logical reasoning skills, making it an important tool in computer science education.
  • Specific Domain Applications: There are many specific applications of prolog in various domains such as:
    • Bioinformatics: to analyze and reason about biological data
    • Robotics: to define rules and reasoning for robot behavior
    • Linguistics: To build model and analyze language structures

According to a report by Grand View Research, the global market for AI in education is expected to reach $6.43 billion by 2028. This highlights the growing demand for AI tools and AI programming languages that support logic-based reasoning and problem-solving areas where Prolog can stay relevant.

Advantages of Prolog

Prolog offers many advantages to AI professionals including:

  • Expressive and concise readable code especially for problems involving logic and reasoning
  • Prolog programming language focuses on what needs to be achieved rather than how to achieve it. Thus, it simplifies program design and reduces complex control flow structures.
  • As it is well suited for knowledge representation and reasoning as facts and rules, it is a natural choice among AI experts

Disadvantages of Prolog

Despite offering several advantages, it comes with a few limitations as well.

  • It has lower performance compared to other languages. They are not so suitable for computationally intensive tasks
  • They have a steeper learning curve because of their declarative nature.


Prolog is one of the finest languages because of its unique approach to programming. They are excellent in tasks involving logic, reasoning, and knowledge representation. Though they are not used mainstream in AI programming, they are still important tools in many specific domains including education.

Their expressiveness, declarative nature, and suitability for knowledge are their greatest strengths and make it a comprehensive language to consider for problems requiring a logical approach.