British mathematician, logician, and computer pioneer. Born in London, he studied at Cambridge University, and Princeton under John von Neumann. He provided a precise mathematical characterization of computability, introducing the theoretical notion of an idealized computer: the Turing machine, in a solution of the Entscheidungsproblem. Turing worked in cryptography during World War II and helped design and program some of the first digital computers. In 1950, he described the Turing Test, which immediately redefined the field of artificial intelligence. He committed suicide after being prosecuted for homosexuality. He knew and was influenced by John von Neumann.