Computing pioneers Alan Turing in England and Claude Shannon in the United States developed fundamental theories of computation that had lasting impact on the field of computing. They also considered chess an interesting puzzle that might help solve other problems and possibly advance the dream of building a machine that could think.
In 1947, before there were computers, Turing designed the first program to play chess and tested it with paper and pencil using himself as the computer. Two years later, Shannon studied two different strategies for building "search trees." The "Type A" strategy considered all possible moves to a fixed depth, and the "Type B" strategy used chess knowledge to explore the more promising lines to a greater depth. Almost all software for two-player games uses either of these strategies.