Variational methods of mathematical physics equations. Discrete infinite-dimensional Hamiltonian systems.
Main publications:
Bak S.N., Pankov A.A., “O periodicheskikh kolebaniyakh beskonechnoi tsepochki lineino svyazannykh nelineinykh ostsillyatorov”, Dopovidi NAN Ukraïni, 9 (2004), 13–16
Bak S. M., Kovtonyuk G. M., “Existence of traveling waves in Fermi–Pasta–Ulam type systems on 2D-lattice”, J. Math. Sci., 252:4 (2021), 453-462
Bak S.M., “Peridoc traveling waves in chains of oscillators”, Communications in Mathematical Analysis, 3:1 (2007), 19–26
Bak S.M., “Existence of solitary traveling waves for a system of nonlinearly coupled oscillators on the 2d-lattice”, Ukr. Math. J., 69:4 (2017), 509-520
Bak S., “The existence of heteroclinic traveling waves in the discrete sine-Gordon equation with nonlinear interaction on a 2D-lattice”, J. Math. Phys., Anal., Geom., 14:1 (2018), 16-26