Introduction to Gray Codes December 2006 CS-860: Formal Languages and Number Theory Introduction to Gray Codes (Summary) An N-bit Gray Code'' is a circular list of 2n N-bit binary numbers, ordered in such a way that each binary number differs from its neighbor by exactly 1 bit (Hamming distance = 1) Invented by Emile Baudot (1845-1903). Named after a research physicist Frank Gray who used the codes for error correction in digital transmissions in 1953. A Position-Absolute code used in electronic sensors. These sensors are implemented in consumer electronic devices as well as many industrial & robotic applications. In 1550 the codes were mentioned as the solution to the Chinese Ring Puzzle. The puzzle has been known in china since at least the 3rd century AD. The reflected binary code is closely related to the solutions of the Towers of Hanoi and Baguenaudier. A more detailed document describing Gray Codes can be downloaded from here Software for the above Gray Code experiment can be downloaded from here . Mark Bramwell CS860: Formal Languages and Number Theory ~ Automatic Sequences Presented by Prof Jeffrey Shallit