In mathematics, the Markov brothers' inequality is an inequality, proved in the 1890s by brothers Andrey Markov and Vladimir Markov, two Russian mathematicians. This inequality bounds the maximum of the derivatives of a polynomial on an interval in terms of the maximum of the polynomial.[1] For k = 1 it was proved by Andrey Markov,[2] and for k = 2,3,... by his brother Vladimir Markov.[3]