 Eberhard Hopf

Eberhard Frederich Ferdinand Hopf (April 17, 1902 in Salzburg, Austria-Hungary – July 24, 1983 in Bloomington, Indiana) was a mathematician and astronomer, one of the founding fathers of ergodic theory and a pioneer of bifurcation theory who also made significant contributions to the subjects of partial differential equations and integral equations, fluid dynamics, and differential geometry.The Hopf maximum principle is an early result of his (1927) that is one of the most important techniques in the theory of elliptic partial differential equations.