Nikolai Aleksandrovich Shanin () (25 May 1919 Pskov – 17 September 2011) was a Russian mathematician who worked on topology and constructive mathematics. He introduced the delta-system lemma and the caliber of a topological space. Further reading External links Nikolai Aleksandrovich Shanin at the Steklov Institute of Mathematics at St. Petersburg Russian mathematicians 1919 births 2011 deaths People from Pskov