FOL is more expressive than PL, it can represent information using relations, variables and quantifies which was not possible with propositional logic.

Syntactic Elements, Semantic and Syntax

Assuming that X is a domain of values, we can define a term with following rules:

a. Constant term: It is a term with fixed value which belongs to the domain.

b. Variable term: It is a term which can be assigned values in the domain.

c. Function: Say f is a function of n arguments. If we assume that t1,t2,..,tn are terms then f(t1, t2,..., tn) is also called a term.

1. All terms are generated by applying the above three protocols.

2. First order predicate logic makes use of propositional logic as a base logic so the connectives used in PL and FOPL are common. Apart from these connectives FOPL makes use of quantifiers like: Universal Quantifiers for all and Existential Quantifiers (there exists)

3. .If a term doesn’t have any variables it is called as a ground term. A sentence in which all the variables are quantified is called as a “well -formed formula”.

4. Interpretation has an objects in the world and a mappings of terms and predicates.

5. Every ground term is mapped with an object.

6. Every condition is mapped to a relation.

7. A ground atom is considered as true if the predicate's relation holds between the term's objects.