| Karol Borsuk | |
|---|---|
| Born | May 8, 1905 Warsaw, Poland, Russian Empire |
| Died | January 24, 1982 (aged 76) Warsaw, Poland |
| Nationality | Poland |
| Fields | Mathematics |
| Alma mater | Warsaw University |
| Doctoral advisor | Stefan Mazurkiewicz |
| Notable students | Samuel Eilenberg Krystyna Kuperberg |
| Known for | Borsuk's conjecture Borsuk-Ulam theorem |
Karol Borsuk (May 8, 1905, Warsaw – January 24, 1982, Warsaw) was a Polish mathematician. His main interest was topology.
Borsuk introduced the theory of absolute retracts (ARs) and absolute neighborhood retracts (ANRs), and the cohomotopy groups, later called Borsuk-Spanier cohomotopy groups. He also founded the so called Shape theory. He has constructed various beautiful examples of topological spaces, e.g. an acyclic, 3-dimensional continuum which admits a fixed point free homeomorphism onto itself; also 2-dimensional, contractible polyhedra which have no free edge. His topological and geometric conjectures and themes stimulated research for more than half a century.
Borsuk received his master's degree and doctorate from Warsaw University in 1927 and 1930, respectively; his Ph.D. thesis advisor was Stefan Mazurkiewicz. He was a member of the Polish Academy of Sciences from 1952. Borsuk's students included Samuel Eilenberg, Krystyna Kuperberg and Włodzimierz Kuperberg.