Fermat, Pierre de 1601-65
French mathematician

Born in Beaumont, he studied law at Toulouse University, where he became a councillor of parliament. His passion was mathematics, most of his work being communicated in letters to friends containing results without proof. His correspondence with Blaise Pascal marks the foundation of probability theory. He studied maximum and minimum values of functions in advance of the differential calculus, but is best known for his work in number theory, the proofs of many of his discoveries being first published by Leonhard Euler a hundred years later. His 'last theorem' is the most famous unsolved problem in mathematics, stating that there are no integers positive x, y, and z with xⁿ+yⁿ =zⁿ if n is greater than 2. In optics Fermat's principle was the first statement of a variational principle in physics, saying that the path taken by a ray of light between two given points is the one in which the light takes the least time.

Bibliography: Michael S Mahoney, The Mathematical Career of Pierre de Fermat 1601-1665 (1973)