9 citations · 15 across the 24 of their papers we have counts for
7 papers · 1 filter
A car as parabolic geometry
C. Denson Hill, Paweł Nurowski
We show that a car, viewed as a nonholonomic system, provides an example of a flat parabolic geometry of type , where is a Borel parabolic subgroup…
Sharp version of the Goldberg-Sachs theorem
A Rod Gover, C Denson Hill, Pawel Nurowski
We reexamine from first principles the classical Goldberg-Sachs theorem from General Relativity. We cast it into the form valid for complex metrics, as well as real metrics of any…
Differential equations and para-CR structures
C. Denson Hill, Pawel Nurowski
We discuss relations between the para-CR structures and differential equations (both ODEs and PDEs of finite type).
Intrinsic geometry of oriented congruences in three dimensions
C Denson Hill, Pawel Nurowski
Starting from the classical notion of an oriented congruence (i.e. a foliation by oriented curves) in , we abstract the notion of an oriented congruence structure. This is a 3…
The Complex Frobenius Theorem for Rough Involutive Structures
C. Denson Hill, Michael Taylor
We establish a version of the complex Frobenius theorem in the context of a complex subbundle S of the complexified tangent bundle of a manifold, having minimal regularity. If the…
On the failure of the Poincaré Lemma for de-bar-sub-M II
C. Denson Hill, Mauro Nacinovich
We obtain very sharp results about the lack of validity of the Poincare lemma for the tangential Cauchy Riemann equations, acting on tangential forms, tangential to a CR manifold M…