Rafael Alexandryan made a significant contribution to the development of the spectral theory of hyperbolic operators. Alexandryan developed the theory of self-adjoint operators. He also proposed a new technique for studying their spectral properties and introduced the concept of a spectrum core. Finally, he reduced the solution of problems of torsion and bending of rods and shafts of variable diameter to non-linear integral and integral-differential Volterra equations of the second kind (together with N. Kh. Harutyunyan and M. M. Manukyan. 1958-1963).
Sergei Adian was the author of the theorem on the unrecognizability of all Markov properties known as the Adian-Rabin theorem. He also authored the main results on algorithmic problems for semigroups with one relationship.
Leonard Oganesyan was an outstanding specialist in numerical analysis and one of the creators of the finite element method (FEM).
Levon Babajanyants published a solution to the Weierstrass problem. In the solution, the n-bodies are represented as series converging at their maximum intervals with arbitrary initial data.
Leonid Khachiyan has lived and worked in the United States since 1989. He proposed the first polynomial algorithm, the ellipsoid method, for solving linear programming problems. Although the algorithm turned out to be unsuitable for practical calculations due to the high degree of the polynomial, the result of Khachiyan is of great theoretical value. In addition, this result gave an impetus to an intensive search for new practical algorithms for solving linear programming problems.
Sergey Mergelyan was an outstanding Armenian scientist, mathematician, and correspondent member of the USSR Academy of Sciences since 1953 and the Armenian Academy of Sciences since 1991. Most importantly, he authored major contributions to approximation theory. In 1952, Mergelyan received the USSR State Prize. In 1956, Mergelyan became an Academician of the Academy of Sciences of Armenia. In 2008, he was awarded the highest state award of Armenia, the Order of St. Mesrop Mashtots.