Kazimierz Kuratowski
Kazimierz Kuratowski (b. February 2, 1896 in Warsaw - d. June 18, 1980 in Warsaw, Poland) was a Polish mathematician.
Kazimierz was since 1927 professor at the Politechnika Lwowska in Lwów and since 1934 at the Warsaw University. In 1945 he became member of the Polish Academy of Skills and in 1952 of the Polish Academy of Science. From 1948 until 1967 he was director of the Institute of Mathematics of the Polish Academy of Science and was also a long-term chairman of the Polish and the International Mathematics Society.
Among his contributions to mathematics are:
- a characterization of Hausdorff spaces in terms of what are now called Kuratowski closure axioms;
- the proof of the Kuratowski-Zorn lemma
- in graph theory, the characterization of planar graphs now known as the Kuratowski's theorem
- The identification of the ordered pair (x,y) with the set {{x},{x,y}}