Sergey Kislitsyn

Sergey Sergeyevich Kislitsyn, born on 5 January 1935 in Ivanovo in the Soviet Union, is a Russian mathematician who specializes in combinatorics and coding theory. He received his master's degree in mathematics from Leningrad State University in 1957 and from 1962 until 1970 worked at the Yekaterinburg branch of the Steklov Institute of Mathematics, now the Krasovsky Institute of Mathematics and Mechanics. He defended his doctoral thesis in 1964 and went on to lecture at Krasnoyarsk State University. He is known for posing, in a paper published in 1968, the 1/3-2/3 conjecture about linear extensions of finite partially ordered sets, which has been proved in several special cases but remains open in full generality.