Nikolai Nikolaevich Luzin (also spelled Lusin; Russian: ??????´? ??????´???? ??´???, IPA: [n??k?'laj n??k?'la?v??t? 'luz??n] (listen); 9 December 1883 – 28 January 1950) was a Soviet/Russian mathematician known for his work in descriptive set theory and aspects of mathematical analysis with strong connections to point-set topology.
He was the eponym of Luzitania, a loose group of young Moscow mathematicians of the first half of the 1920s.
They adopted his set-theoretic orientation, and went on to apply it in other areas of mathematics.