ABSTRACT
A comparatively large number of workers are employed in artificial intelligence (AI) in Portugal. It is clear that the Prolog language played a very important role in this development. AI research in Portugal has been mainly of an academic nature and has been conducted mostly by university teachers who had to combine research with their lecturing and administrative duties. Prolog was originally introduced by A. Colmerauer in 1972 at the University of Marseille, and was based on R. Kowalski's concept of "logic programming". One of the distinctive features of Prolog as a programming language is that it is modeled after a powerful but simple mathematical model, namely the semi-decidable set of Horn clauses of first-order predicate calculus. Prolog offers a modular and incremental programming style. This means that programs can grow consistently from a small set of clauses, with the obvious benefit of less debugging work.
