Beginning in 1930 he dedicated himself to the study of differential equations, the first to use a topological-functional approach.

Her later work involved the study of elliptical and parabolic equations that are used in probability theory.

The general solution comes from the study of ordinary differential equations and can be solved by the use of a Green's function.

Historically, however, they arose in the study of quadratic forms and differential equations.

The second research area is specialized in the study of partial differential equations from a theoretical viewpoint, but also in their applications.

This point of view turned out to be particularly useful for the study of differential and integral equations.

Semi-infinite regions occur frequently in the study of differential equations.

It is useful in the study of partial differential equations.

The notion of flow is basic to the study of ordinary differential equations.

It is very common in many fields, including engineering, physics and the study of differential equations, to use a notation that makes the flow implicit.