Alain Colmerauer and Philippe Roussel Create Prolog

Ah, the era of symbolic AI boom. It continues.

In the fall of 1972, Philippe Roussel implemented the first Prolog in Marseille for Alain Colmerauer’s project to reason with a computer in French. The name, suggested by Roussel’s wife, abbreviates programmation en logique.

A Prolog program was a set of facts and rules in logic. It ran by asking a question it answered by proof, backtracking when a line of reasoning fails. This was not too dissimilar to the English logic program STRIPS, by Richard Fikes and Nils Nilsson at Stanford Research Institute and mentioned previously in this timeline (STRIPS).

The first large Prolog program, 610 clauses by Colmerauer, Robert Pasero and Henry Kanoui, answered questions about short French texts. Prolog was successful enough as Japan’s 1982 Fifth Generation Computer Systems initiative took logic programming, and Prolog in particular, as its basis.