Mark Semenovich Pinsker wrote a classic paper on the entropy theory of dynamical systems which introduced the maximal partition with zero entropy; in addition to this, he also invented Pinsker's inequality (an inequality that bounds the total variation distance in terms of the KullbackLeibler divergence).
His accomplishments included a classic paper on the entropy theory of dynamical systems which introduced the maximal partition with zero entropy, later known as Pinsker's partition. His work in mathematical statistics was devoted mostly to the applications of information theory, including asymptotically sufficient statistics for parameter estimation and nonparametric estimation; Pinsker's inequality is named after him. In information theory, Pinsker's inequality, named after its inventor Mark Semenovich Pinsker, is an inequality that bounds the total variation distance (or statistical distance) in terms of the KullbackLeibler divergence. 
