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Solving Post's unsolvable problem leads to the 'Minsky Machines'


Solving Emil Post's problem
Marvin Minsky Scientist
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I’m trying to think of a few parallels, but generally, if you’re very good at something and you find somebody who’s better, then you should figure out something else your skill set is good for and it turned out that I was also interested in the foundations of logic and computation and I had discovered some interesting things about that... and then... a mathematician named Martin Davis, who had been a friend of mine for some years, told me about a problem that was... had been generated by a professor at NYU, Emil Post, in the 1920s and he wrote a paper in 1923 conjecturing something about a certain kind of logical system and... long before Alan Turing had published anything, Post had published something about how he thought maybe this was an unsolvable problem. Also Gödel had... Gödel was 1931 and Gödel had the first proof of what’s called a recursively unsolvable problem, but Post had sort of pioneered in that area in the 1920s and discovered something which he conjectured was unsolvable, but Gödel was the first one to prove anything and then Turing in 1936 – Alan Turing – had come up with a much simpler proof of an unsolvable problem that... something that a computer couldn’t do and I didn’t know about Post’s work, but Martin Davis had been a student of him at... at NYU and out of the blue Davis phoned me and said: 'There’s a problem that Emil Post and I couldn’t solve, but I think you might have the skill set for that.' The funny part is that I mentioned this to Davis a few years ago and he said: 'I... I never did that, I don’t remember telling you.' But I remember fairly clearly that I never heard of Post’s problem and that Davis told me about it because he thought that I might be able to solve it and indeed I did. So I published a paper in 1961 solving this interesting old problem of Emil Post.

Marvin Minsky (1927-2016) was one of the pioneers of the field of Artificial Intelligence, founding the MIT AI lab in 1970. He also made many contributions to the fields of mathematics, cognitive psychology, robotics, optics and computational linguistics. Since the 1950s, he had been attempting to define and explain human cognition, the ideas of which can be found in his two books, The Emotion Machine and The Society of Mind. His many inventions include the first confocal scanning microscope, the first neural network simulator (SNARC) and the first LOGO 'turtle'.

Listeners: Christopher Sykes

Christopher Sykes is a London-based television producer and director who has made a number of documentary films for BBC TV, Channel 4 and PBS.

Tags: NYU, 1923, 1931, 1961, 1936, Emil Post, Martin Davis, Alan Turing, Kurt Gödel

Duration: 3 minutes, 1 second

Date story recorded: 29-31 Jan 2011

Date story went live: 12 May 2011