Arthur Sard

Arthur Sard (28 July 1909, New York City – 31 August 1980, Basel) was an American mathematician, famous for his work in differential topology and in spline interpolation. His fame stems primarily from Sard's theorem, which says that the set of critical values of a differential function which has sufficiently many derivatives has measure zero.

Arthur Sard was born and grew up in New York City and spent most of his adult life there. He attended the Friends Seminary, a private school in Manhattan, and went to college at Harvard University, where he received in 1931 his bachelor's degree, in 1932 his master's degree, and in 1936 his PhD under the direction of Marston Morse. Sard's PhD thesis has the title The measure of the critical values of functions. He was a member of the first faculty members at the then newly founded Queens College, where he worked from 1937 to 1970.

During WWII Sard worked as a member, under the auspices of the Applied Mathematics Panel, of the Applied Mathematics Group of Columbia University (AMG-C), especially in support of fire control for machine guns mounted on bombers. Saunders Mac Lane wrote concerning Sard: “His judicious judgments kept AMG-C on a straight course, […]”.

Sard retired as professor emeritus in 1970 at Queens College and then worked at La Jolla, where he spent five years as a research associate in the mathematics department of the University of California, San Diego. In 1975 he went to Binningen near Basel and taught at various European universities and research institutes. In 1978 he accepted an invitation from the Soviet Academy of Sciences to be a guest lecturer. In 1978 and 1979 he was a guest professor at the University of Siegen. Arthur Sard died on 31 August 1980 in Basel.

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