Topological embeddings in Euclidean space
The torsions of a general connection on the th-order tangent bundle of a manifold are defined as the Frölicher-Nijenhuis bracket of with the natural affinors. The author deduces the basic properties of these torsions. Then he compares them with the classical torsion of a principal connection on the th-order frame bundle of .
[For the entire collection see Zbl 0699.00032.] A fibration is called totally noncohomologuous to zero (TNCZ) with respect to the coefficient field k, if is surjective. This is equivalent to saying that acts trivially on and the Serre spectral sequence collapses at . S. Halperin conjectured that for and F a 1-connected rationally elliptic space (i.e., both and are finite dimensional) such that vanishes in odd degrees, every fibration is TNCZ. The author proves this being the case...
Des liens inattendus ont été récemment mis à jour entre le transport optimal de Monge–Kantorovich et certains problèmes de géométrie riemannienne, en liaison avec la courbure de Ricci. Une des retombées de ces interactions est la naissance d’une théorie « synthétique » des espaces métriques mesurés à courbure de Ricci minorée, venant compléter la théorie classique des espaces métriques à courbure sectionnelle minorée. Dans ce texte (également fourni aux actes du Séminaire d’Équations aux dérivées...
For the entire collection see Zbl 0699.00032.
Summary: We describe explicitly the kernels of higher spin twistor operators on standard even dimensional Euclidean space , standard even dimensional sphere , and standard even dimensional hyperbolic space , using realizations of invariant differential operators inside spinor valued differential forms. The kernels are finite dimensional vector spaces (of the same cardinality) generated by spinor valued polynomials on .