4-Facts || No vs False [PROLOG]

Introduction

This tutorial aims to clarify the concepts of "No" and "False" in Prolog, enhancing your understanding of logical facts. By grasping these ideas, you will be better equipped to build a knowledge base in Prolog, which is essential for effective programming in this logic-based language.

Step 1: Understanding Facts in Prolog

• Facts are basic assertions that are always true in Prolog.
• They represent knowledge in the system, which can be queried later.
• Examples of facts include:
  • cat(tom). (This states that Tom is a cat.)
  • likes(anna, pizza). (This states that Anna likes pizza.)

Practical Tips

• Keep your facts simple and clear.
• Use descriptive names for better readability.

Step 2: Differentiating Between No and False

• No: Indicates the absence of a certain condition or fact.
• False: Represents a condition that is unequivocally untrue.

Examples

• If you query likes(john, ice_cream). and the system responds with "No," it means that there is no information about John liking ice cream.
• If you have a fact like likes(jane, chocolate). and then ask if likes(jane, chocolate) = false., the response will be false since the fact exists.

Step 3: Building a Knowledge Base

• To build a knowledge base, start by defining your facts clearly.
• Consider relationships and use predicates effectively to represent these facts.

Key Points for Building

• Use predicates to illustrate relationships:
  • parent(john, mary). (John is the parent of Mary.)
• Ensure that your facts are logically consistent to avoid confusion.

Step 4: Querying Your Knowledge Base

• Use queries to retrieve information from your knowledge base.
• Queries can be simple or complex based on your needs.

How to Query

• Start with basic queries:
  • ?- cat(tom). (This checks if Tom is a cat.)
• Use conditions to check relationships:
  • ?- likes(anna, X). (This retrieves what Anna likes.)

Conclusion

In this tutorial, you learned the foundational concepts of facts, the difference between "No" and "False," and how to build and query a knowledge base in Prolog. Understanding these elements is crucial for effective programming in Prolog.

Next steps can include exploring more complex queries and relationships, as well as practicing building a more extensive knowledge base. Stay tuned for more advanced Prolog tutorials!