Growth theory of entire functions. De Branges spaces. Canonical sys-
tems and their special cases (Jacobi matrices, Schrödinger operators). Direct spec-
tral theory of canonical systems. De Branges version of Phragmén–Lindelöf theorem.
Ordering theorem for de Branges spaces. Inverse spectral theory in the regular case.
Direct and inverse spectral problems in the singular case.