Predicate Logic in Artificial Intelligence

Predicate Logic

Every complete sentence contains two parts –
Subject: The subject is what or whom the sentence is about.

Predicate: It tells something about the subject. sentence involving the predicates that describe the property of objects are denoted by P(x) where
P – The Predicate
x – It is a variable denoting any object.

Characteristics of Predicate Logic

1. Logical inferencing is allowed.
2. More accurate KR of facts of the real world.
3. Program designing is its application area.
4. Better theoretical foundation.
5. A predicate with no variable is called a Ground Atom.

Rules of Predicate calculus symbols

1. Set of letters (uppercase or lowercase) is allowed.
2. Set of digits (0-9) is allowed.
3. Underscore (_) is allowed.
4. Blanks and non-alphanumeric characters can’t be used.
5. Special characters like $, *, #, and / are not allowed.

Symbols

1. Predicate Symbols: It denotes relations or functional mapping from the elements of a domain to the values true or false.

2. Function Symbols: It denotes relations defined on a domain.

3. Variable Symbols: Lowercase unsubscribed or subscribed letters like x, y, z, t, u, v, etc. It can assume different values over a given domain.

4. Constants: It is fixed value term. They are individual symbols which are names of objects like 1, 2, 3, etc.

5. Quantifiers: There are two types of Quantifiers:
i. Existential Quantifier (Ǝ): It means for some x or there is no x.
ii. Universal Quantifier (∀): It means for all x.

6. Logical Operators: There are five type of logical operators such as – not(~), and (^), or(v), implication, equivalence.