Prolog
Colmerauer and Roussel create a language in which a program is a set of logical facts and rules, and running it is proving a theorem.
what had to happen · 5 events back to 1943
Every event this one built on, transitively, in order. Direct influences are marked.
00 · One neuron · 1
I · Foundations · 4
Lisp gave AI a language for symbols. Prolog, written in Marseille in the summer of 1972 by Alain Colmerauer and Philippe Roussel with the logician Robert Kowalski in Edinburgh, gave it a language for logic. A Prolog program is a list of facts and rules in a restricted form of first-order logic. You ask it a question and it searches for a proof, backtracking through the alternatives, and the proof is the answer. The programmer states what is true; the machine works out how.
It was the natural language for the knowledge-based systems of the 1970s and 80s, and in 1982 the Japanese government chose it as the foundation of the Fifth Generation Computer Systems project, a ten-year national programme to build machines that reasoned in parallel. When that programme ended in 1992 without the promised machines, Prolog's reputation went down with it.
The idea outlived the language. Constraint solving, database query languages and the logical layer of the semantic web all descend from Prolog, and the 2020s revived interest in combining learned models with exactly the kind of explicit, checkable reasoning it was built for.
what it led to · 3 events downstream, through 1992
Built on it directly:
And, through them, by era: