programming in logic (PROLOG)

PROLOG (Programming in Logic) is a predictive programming language that originated in the 1970s and is still in use today, with many free and commercial implementations. When it was first developed, Prolog was declared for natural language processing; however, its applications have expanded considerably to include knowledge processing, expert systems, artificial intelligence( AI), computer games, call answering systems, and other intelligent applications such as graphical user interface( GUI) development.

In predictive programming languages, knowledge about the problem is formulated, and the program uses the knowledge in a database to search for a solution to the posed problem. The knowledge itself is composed of basic elements defined by facts and rules. These basic elements have a logical relationship to each other, defined by clauses. Such a relationship can be, for example, a person's name in connection with age like pensioner (klaus), baby (samantha), student (benjamin) or the reference in the family hierarchy like grandfather (klaus), granddaughter (samantha), grandson (benjamin). In Prolog, these relations to each other are queried and confirmed or refuted by the interpreter. Prolog answers questions with "yes" or "no", depending on whether the query was able to establish a relational connection from the database or not.

The Prolog programming language is the subject of a draft ISO standard adopted in 1992 and led to ISO Prolog.