Alan Turing is one of the world’s best-known mathematicians, and probably the best known in the past century. This is partly for his work on cracking German codes in World War II, and partly for his arrest, conviction and punishment for homosexuality in the 1950s. The mathematics that made him famous, however, rarely gets mentioned.
His early work, which is more theoretical in nature, set the foundations for the concept of a modern computer. He then went on to actually start building these computers, mostly during World War II, and this is the part of Turing’s life that is most often talked about.
After the war, he had a brief spell working on real-life computers before thinking about artificial intelligence. This is when the famous Turing Test appeared, and it was just before the other part of his life that is normally discussed – his conviction for homosexuality, chemical castration and suicide.