Alexander Sergeyevich Esenin-Volpin was born on May 12, 1924, and died on March 16, 2016.

He was a prominent Russian-American poet and mathematician.

Volpin was a notable dissident, political prisoner and a leader of the Soviet human rights movement, he spent a total of 14 years incarcerated and repressed by the Soviet authorities in prisons, psikhushkas and exile.

Alexander Esenin-Volpin early work was on general topology, where he introduced Esenin-Volpin’s theorem.

A majority of his later work was on the foundations of mathematics, where he introduced ultrafinitism, an extreme form of constructive mathematics that casts skepticism on the existence of not only infinite sets, but even of large integers such as 1012.

Alexander sketched a program for proving the consistency of Zermelo–Fraenkel set theory using ultrafinitism techniques in (Ésénine-Volpine 1961), (Yessenin-Volpin 1970) and (Yessenin-Volpin 1981).

Alexander Esenin-Volpin passed away at 91 yrs old.