The first recommendation to use a clausal form of logic for representing computer programs was made by Cordell Green (1969) at Stanford Research Institute (now SRI International).
This idea can also be linked back to the battle between procedural and declarative information representation in early artificial intelligence systems.
As input, a predicate takes any object(s) in the domain of interest and outputs either one of two Boolean values: true or false.
Either of these sentences can be broken down into predicates which can be compared and form the knowledge base of a deductive language.
Depending on the language, the order of declaration of these predicates within the knowledge base may or may not influence the result of applying logical rules.
Prolog is an example of a deductive, declarative language that applies first- order logic to a knowledge base.