In brief
William Feller (July 7, 1906 – January 14, 1970), born Vilibald Srećko Feller in Zagreb (then part of Austria-Hungary, now Croatia), was a mathematician whose rigorous application of measure theory transformed probability into a foundational discipline of modern mathematics.
Educated at the University of Zagreb and earning his Ph.D. from the University of Göttingen in 1927, Feller held positions at institutions including Brown University (1939–1945), Cornell University (1945–1950), and Princeton University (1950–1970), where he served as Eugene Higgins Professor of Mathematics. His seminal contributions included developing necessary and sufficient conditions for the central limit theorem, advancing the law of the iterated logarithm, and elucidating connections between Markov processes, diffusion, and partial differential equations, alongside pioneering work on Brownian motion and boundary conditions for stochastic processes.
Eugen Viktor's background included a Polish-Jewish paternal grandfather (David Feller) and an Austrian maternal grandmother (Elsa Holzer), reflecting the family's mixed ethnic and religious origins in a multi-ethnic region.
