Sergei Aleksandrovich Stepanov (Сергей Александрович Степанов; [1] 24 February 1941) is a Russian mathematician, specializing in number theory.
He is known for his 1969 proof using elementary methods of the Riemann hypothesis for zeta-functions of hyperelliptic curves over finite fields, first proved by André Weil in 1940–1941 using sophisticated, deep methods in algebraic geometry.
Stepanov received in 1977 his Russian doctorate (higher doctoral degree) from the Steklov Institute under Dmitry Konstantinovich Faddeev with dissertation (translated title) An elementary method in algebraic number theory.
Wolfgang M. Schmidt extended Stepanov's methods to prove the general result, and Enrico Bombieri succeeded in using the work of Stepanov and Schmidt to give a substantially simplified, elementary proof of the Riemann hypothesis for zeta-functions of curves over finite fields.
[4][5][6] Stepanov's research also deals with applications of algebraic geometry to coding theory.