Fig. 1: Alan Turing

Developments of particular interest as far as the birth of AI is concerned come in the mid 20th century. They were due to Alan Turing (1912-1954), who made two fundamental contributions. In 1936 he proposed a model for a universal automatic calculator (known as Turing's machine): it is the prototype of all electronic computers developed in the mid 1940s. In 1950 Turing proposed the imitation game, a paradigm to establish if a machine is intelligent or not. In a well-known article of his, Computing Machinery and Intelligence (1950), he suggests placing an observer in front of two teleprinters. One of the two teleprinters is run by a man, the other by a woman. The observer, who does not know which is commanded by the man and which by the woman, tries to work it out by asking them any kind of question. One of the two interlocutors must tell the truth, the other should pretend to be of the opposite sex. At a certain point the interlocutor who is lying is replaced with a calculator programmed to pretend to be a human being. When the number of mistakes made in trying to identify the computer is the same as those made in trying to identify the lying interlocutor, then the computer can be called intelligent.

Historical outlines:

• 1943: First AI work: Warren McCulloch and Walter Pitt design a neural network.
• 1956: John McCarthy gathers the main scholars of the time in Dartmouth (among them Marvin Minsky, Allen Newell, Claude Shannon and Herbert Simon) for a seminary, where he proposes the name artificial intelligence.
• 1958: McCarthy produces the Lisp, a high level programming language dedicated especially to AI.
• 1970-1980: Important developments in research on neural networks. At the same time the first difficulties also arise; one serious problem is the combinatory burst, the sudden increase of calculation time when the number of variables increases in a problem.
  The first expert systems are designed with applications for medical diagnostics, and lead to the first attempts to understand natural language.
• 1973: Recent results on the resolution method (by J.A. Robinson) give birth to Prolog,
• 1980-today: AI comes out of the science laboratories and finds significant practical applications. At the same time, as a consequence, industrial companies especially in America and Japan start to market programs focusing on expert systems, on configuration recognition and so on, building microcircuits and whole computers specialised in AI applications.