Columbia subject headings:
Differential equations, Partial--Asymptotic theory.
Homology theory.
Pfaffian problem.
Sheaf theory.
Harvard subject headings:
Differential equations, Partial--Asymptotic theory.
Homology theory.
Pfaffian problem.
Sheaf theory.
Princeton subject headings:
Differential equations, Partial--Asymptotic theory.
Homology theory.
Pfaffian problem.
Sheaf theory.