In comparison Prolog has a certain type of object relation called a selector which allows the user to access certain components of a family of objects with the full details of it. The name of the selector is that of the component being selected. These relations allow us to ignore the amount of the information in the object family. We only need to know the name of the selector relations. Although with more complicated representations this method is much easier than using explicit references.
Selectors also make it easier to modify programs.
So therefore by simply modifying the selector statement definitions we can make changes without modifying the rest of the program. LISP was designed by McCarthy and Minsky of the MIT AI Project in the 1950s. ML was designed by Milner and The University of Edinburgh in the 1980s. Logic Based languages include languages such as Prolog. The basic design for Prolog was developed by Colmerauer and Roussel of the AI group at the University of Aix-Marseille, and Kowalski and the AI department at The University of Edinburgh.