**Figure 1**. Alan Turing (1912-1954) (*Source:* MacTutor History of Mathematics Archive)

The British mathematician Alan Turing has perhaps achieved greater fame today than during his lifetime. Thirty-two years after his death in 1954 a play based on part of his work, *Breaking the Code*, opened in London’s West End theater district; it played in New York the next year. The Broadway production was nominated for three Tony Awards, a rare accomplishment for a theatrical piece about a mathematician. But Turing was no ordinary mathematician. The play deplored his sad demise apparently caused by his homosexuality. More recently, the movie *The Imitation Game* depicted Turing’s early education, role in deciphering Enigma in World War II, and the tragedy of his death at age 41. Here I describe how two of his greatest accomplishments were influenced by one of his two visits to the U.S.

The authoritative account of the life and career of Alan Turing is a book by Andrew Hodges [**10**]. Two more recent works from different viewpoints are [**3**] and [**11**]. In addition, online files from a Princeton conference held to commemorate Turing’s 100th birthday can be accessed at: http://www.princeton.edu/turing/