Linear ordinary differential equations of order n
Construction of the Weyl algebra (noncommutative “differential polynomials of one independent variable”). Division with remainder, factorization, solutions.
Reconstruction of differential equations from their solutions. Riemann theorem.
Regular and Fuchsian operators. Complete local reducibility. Fuchs theorem (local regularity local Fuchs property) and its reformulations.
Recommended reading: Section 19 from the book (printing disabled)