A Symbolic Analysis of Relay and Switching Circuits

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In his 1937 MIT master's thesis, A Symbolic Analysis of Relay and Switching Circuits, Claude Elwood Shannon proved that Boolean algebra and binary arithmetic could be used to simplify the arrangement of the electromechanical relays then used in telephone routing switches, then turned the concept upside down and also proved that it should be possible to use arrangements of relays to solve Boolean algebra problems. This concept, of utilizing the properties of electrical switches to do logic, is the basic concept that underlies all electronic digital computers, and the thesis became the foundation of practical digital circuit design when it became widely known among the electrical engineering community during and after World War II. Methods to design logic circuits at the time were ad hoc and lacked the theoretical rigor that Shannon's paper supplied to later projects.

Professor Howard Gardner, of Harvard University, called Shannon's thesis "possibly the most important, and also the most famous, master's thesis of the century". A version of the paper was published in the 1938 issue of the Transactions of the American Institute of Electrical Engineers, and in 1940, it earned Shannon the Alfred Noble American Institute of American Engineers Award.