Hvem daterte 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 Sergeyevich Alexandrov (Russian: Па́вел Серге́евич Алекса́ндров), sometimes romanized Paul Alexandroff (7 May 1896 – 16 November 1982), was a Soviet mathematician. He wrote roughly three hundred papers, making important contributions to set theory and topology. In topology, the Alexandroff compactification and the Alexandrov topology are named after him.