Felix Hausdorff

Born Nov. 8, 1868, in Breslau, now Wroclaw; died Jan. 26, 1942, in Bonn. German mathematician.

Hausdorff graduated from the University of Leipzig in 1891. He assumed a teaching position at the university in 1895 and was appointed a professor in 1902. He subsequently became a professor at the University of Greifswald and, in 1921, at the University of Bonn.

Hausdorff made important contributions to set theory, topology, functional analysis, the theory of continuous groups, and number theory. In his Essentials of Set Theory (1914) he gave the first definition, and provided a systematic study, of a class of topological spaces, now called Hausdorff spaces, that have assumed a fundamental position in mathematics. He thus may be regarded as the founder of modern general topology. In 1916, Hausdorff, simultaneously with and independently of P. S. Aleksandrov, solved the problem of the cardinality of Borel sets. He also contributed the concept of the measure of a set, the concept of topological limit, and numerous theorems of set theory, general topology, mathematical analysis, and the theory of Lie groups.

In 1942, after learning that he and his family would soon be sent to one of Hitler’s concentration camps, Hausdorff committed suicide.