Ποιος χρονολόγησε Pavel Urysohn;

Pavel Samuilovich Urysohn (in Russian: Па́вел Самуи́лович Урысо́н; 3 February 1898 – 17 August 1924) was a Soviet mathematician who is best known for his contributions to the theory of topological dimension, and for developing Urysohn's metrization theorem and Urysohn's lemma, both of which are fundamental results in topology. He also constructed what is now called the Urysohn universal space and his name is also commemorated in the terms Fréchet–Urysohn space, Menger–Urysohn dimension and Urysohn integral equation. He and Pavel Alexandrov formulated the modern definition of compactness in 1923.

Pavel Sergueïevitch Aleksandrov (en russe : Павел Сергеевич Александров, autre orthographe : Alexandrov ou Alexandroff) (1896-1982) est un mathématicien soviétique.

Il est élu membre en 1953 de l'Académie des sciences d'URSS. Il a largement contribué aux domaines de la théorie des ensembles et de la topologie.