Aleksandr Lyapunov was born on June 6, 1857 in Yaroslavl, Russia. He was a friend of Andrei Markov, and both were students of Pafnuty Chebyshev.
Lyapunov made important contributions in differential equations, potential theory, stability of systems, numerical analysis, and fluid dynamics. To students, he is best known for his method of determining the satiability of a set of differential equations, and for the inequality relating the norms of functions that now bears his name.
Lyapunov died on November 3, 1918 in Odessa, Russia.