Hellmuth Kneser

Hellmuth Kneser was an Estonian-born German mathematician who worked across an unusually wide range of mathematics and is best known for his work in group theory and topology. Born in Dorpat in 1898, he was the son of the mathematician Adolf Kneser, studied at Breslau and then at Goettingen, where David Hilbert directed his doctoral work on the mathematics of quantum mechanics. He held chairs at Greifswald from 1925 and at Tuebingen from 1937. By choice he refused to specialise, and he published on sums of squares in fields, groups, non-Euclidean geometry, almost periodic functions, the iteration of analytic functions, the differential geometry of manifolds and the value distribution of meromorphic functions. In 1950 he gave a solution to a functional equation of the form f(f(x)) = e to the x, and between 1958 and 1964 he studied manifolds without a countable basis of neighbourhoods. He helped found and later led the Oberwolfach research institute, edited several mathematical journals, and was president of the German Mathematical Society. His son Martin Kneser was also a mathematician.