Since June 2020 A.A. Shkalikov has been holding the position of a RMC senior researcher and an external expert. He is a prominent Soviet and Russian mathematician who gained world recognition in the field of operator theory and its applications in mechanics and mathematical physics, theory of spaces with an indefinite metric, function theory, function theory of one complex variable. His research findings shaped the vision on contemporary spectral theory of operators. Approaches and methods introduced by the scientist allow to solve new problems of abstract operator theory and are applicable to mathematical physics, quantum mechanics, theory of elasticity and hydrodynamics.