Fritz John

Fritz John (1910 to 1994) was a German-born mathematician who worked in partial differential equations and ill-posed problems. Born in Berlin, he studied at Gottingen from 1929 to 1933, where Gustav Herglotz, Richard Courant and Hans Lewy influenced him most, and took his doctorate there in 1934. Because of his Jewish descent he left Germany after the Nazi rise to power, spent a year at St John's College, Cambridge, and then lectured at the University of Kentucky from 1935, becoming a United States citizen in 1941. After war service at the Ballistic Research Laboratory at Aberdeen Proving Ground he joined New York University in 1946 and stayed for the rest of his life, holding the Courant Chair from 1978. His early work concerned the Radon transform, which he applied to linear partial differential equations, convex geometry and the theory of water waves; later he studied ill-posed problems, nonlinear elasticity, functions of bounded mean oscillation and nonlinear wave equations. He received the Birkhoff Prize in Applied Mathematics in 1973.