Hans Fitting

Hans Fitting was a German algebraist who worked mainly in group theory and the theory of rings and modules, and who died of bone cancer in 1938 at the age of thirty-one. The son of a schoolteacher and amateur mathematician who taught him at school, he studied at Tübingen and Göttingen and took his doctorate in 1932 under Emmy Noether with a dissertation on the automorphism rings of abelian groups and their analogue for non-commutative groups. He then worked at Königsberg, where he habilitated in 1936 and became a lecturer in 1937. His name survives in several standard objects: the Fitting subgroup, the unique largest normal nilpotent subgroup of a finite group, which gives rise to the Fitting length; Fitting's lemma on products of normal nilpotent subgroups; and the Fitting ideals of a module, introduced in his 1936 paper on determinant ideals. He also gave a proof of the Remak-Krull-Schmidt theorem on direct product decompositions that extends to groups with operators. MacTutor describes a meticulous and reflective worker whose short career left lasting results.