Aleksandr Lyapunov

Aleksandr Mikhailovich Lyapunov His surname is variously romanized as Ljapunov, Liapunov, Liapounoff or Ljapunow.}}}} (Алекса́ндр Миха́йлович Ляпуно́в, – 3 November 1918) was a Russian mathematician, mechanician and physicist. He was the son of the astronomer Mikhail Lyapunov and the brother of the pianist and composer Sergei Lyapunov.

Lyapunov is known for his development of the stability theory of a dynamical system, as well as for his many contributions to mathematical physics and probability theory. Provided by Wikipedia