Five-dimensional para-CR manifolds and contact projective geometry in dimension three
Five-dimensional para-CR manifolds and contact projective geometry in dimension three
We study invariant properties of 5-dimensional para-CR structures whose Levi form is degenerate in precisely one direction and which are 2-nondegenerate.We realize that two, out of three, primary (basic) para-CR invariants of such structures are the classical differential invariants known to Monge (1810) and to Wünschmann (1905):The vanishing M(G) ≡ …