History of mathematics and mechanics; analysis from 1700, in particular the calculus of variations; foundations of mathematics; Leonhard Euler, Jean d'Alembert, Joseph Louis Lagrange, Augustin Cauchy, William Rowan Hamilton, Carl Gustav Jacobi, Adolph Mayer, Karl Weierstrass, Henri Poincaré. Classification of mathematical knowledge, LC, MSC. Modern cosmology, interactions of theoretical and observational cosmology 1900-1965.