Horst Schubert

{{Short description|German mathematician}}

Horst Schubert (11 June 1919 – 2001){{Cite book | url=https://books.google.com/books?id=F5qIAwAAQBAJ&q=horst+schubert+1919-2001&pg=PA383 |title = Low-Dimensional Geometry: From Euclidean Surfaces to Hyperbolic Knots|isbn = 9780821848166|last1 = Bonahon|first1 = Francis|date = 2009-07-14}} was a German mathematician.

Schubert was born in Chemnitz and studied mathematics and physics at the Universities of Frankfurt am Main, Zürich and Heidelberg, where in 1948 he received his PhD under Herbert Seifert with thesis Die eindeutige Zerlegbarkeit eines Knotens in Primknoten.[https://books.google.com/books/about/Die_Eindeutige_Zerlegbarkeit_Eines_Knote.html?id=ErRvQgAACAAJ Die eindeutige Zerlegbarkeit eines Knotens in Primknoten, dissertation published 1 Jan. 1949]{{MathGenealogy|id=21623}} From 1948 to 1956 Schubert was an assistant in Heidelberg, where he received in 1952 his habilitation qualification. From 1959 he was a professor extraordinarius and from 1962 a professor ordinarius at the University of Kiel. From 1969 to 1984 he was a professor at the University of Düsseldorf.

In 1949 he published his proof that every oriented knot in $S^3$ decomposes as a connect-sum of prime knots in a unique way, up to reordering.Schubert, H. Die eindeutige Zerlegbarkeit eines Knotens in Primknoten. S.-B Heidelberger Akad. Wiss. Math.-Nat. Kl. 1949 (1949), 57–104. After this proof he found a new proof based on his study of incompressible tori in knot complements; he published this work Knoten und Vollringe in Acta Mathematica, where he defined satellite and companion knots.Schubert, H. Knoten und Vollringe. Acta Math. 90 (1953), 131–286. His doctoral students include Theodor Bröcker.