In blessed memory of the scientist, educator, teacher - Mykola Oleksiĭovych Perestyuk (Q6648622)

A short description of the life and scientific path of academician of the National Academy of Sciences of Ukraine, honored doctor of Yuriĭ Fed'kovych Chernivtsi National University Mykola Oleksiĭovych Perestyuk (January 1, 1946 -- January 25, 2024) is presented. The scientific interests of M. O. Perestyuk cover a wide range of complex and relevant problems of the theory of differential equations and nonlinear mechanics, which relate to the development of a new direction of this theory, namely differential equations with impulse action, their application to the study of oscillatory processes. He established effective criteria for the stability of solutions of differential equations subjected to impulse effects, developed algorithms for the approximate solution of a wide class of impulse differential equations, proposed a method for studying the properties of solutions and integral sets of systems of differential equations with impulse action on surfaces, formulated and substantiated the signs of the existence of important types of single- and multi-frequency discontinuous oscillations in non-classical differential systems. See, for example, \textit{A. M. Samoilenko} and \textit{N. A. Perestyuk}, Impulsive differential equations. Singapore: World Scientific (1995; Zbl 0837.34003).