Flag Manifolds
The aim of this work is to study global -webs with vanishing curvature. We wish to investigate degree foliations for which their dual web is flat. The main ingredient is the Legendre transform, which is an avatar of classical projective duality in the realm of differential equations. We find a characterization of degree foliations whose Legendre transform are webs with zero curvature.
We determine the flat tensor product surfaces of two curves in pseudo-Euclidean spaces of arbitrary dimensions.
In spaces of nonpositive curvature the existence of isometrically embedded flat (hyper)planes is often granted by apparently weaker conditions on large scales.We show that some such results remain valid for metric spaces with non-unique geodesic segments under suitable convexity assumptions on the distance function along distinguished geodesics. The discussion includes, among other things, the Flat Torus Theorem and Gromov’s hyperbolicity criterion referring to embedded planes. This generalizes...
We study the prolongation of semibasic projectable tangent valued -forms on fibered manifolds with respect to a bundle functor on local isomorphisms that is based on the flow prolongation of vector fields and uses an auxiliary linear -th order connection on the base manifold, where is the base order of . We find a general condition under which the Frölicher-Nijenhuis bracket is preserved. Special attention is paid to the curvature of connections. The first order jet functor and the tangent...
[For the entire collection see Zbl 0699.00032.] The author defines a general notion of a foliated groupoid over a foliation with singularities, within the framework of a (known) general notion of a differentiable structure. Then, he generalizes the classical correspondence between the subalgebras of Lie algebras and the subgroups of the corresponding Lie groups for this type of pseudogroups.