Simplified multitime maximum principle.
We give necessary and sufficient local conditions for the simultaneous unitarizability of a set of analytic matrix maps from an analytic 1-manifold into under conjugation by a single analytic matrix map.We apply this result to the monodromy arising from an integrable partial differential equation to construct a family of -noids, genus-zero constant mean curvature surfaces with three or more ends in euclidean, spherical and hyperbolic -spaces.
Let be a 4-dimensional Einstein Riemannian manifold. At each point of , the tangent space admits a so-called Singer-Thorpe basis (ST basis) with respect to the curvature tensor at . In this basis, up to standard symmetries and antisymmetries, just components of the curvature tensor are nonzero. For the space of constant curvature, the group acts as a transformation group between ST bases at and for the so-called 2-stein curvature tensors, the group acts as a transformation group...
Locally exact complexes of invariant differential operators are constructed on the homogeneous model for a parabolic geometry for the even orthogonal group. The tool used for the construction is the Penrose transform developed by R. Baston and M. Eastwood. Complexes constructed here belong to the singular infinitesimal character.
We introduce topological 𝒬-holonomy groupoids for singular foliations (M,ℱ) with an Ehresmann connection 𝒬 using 𝒬-holonomy groups, which have a global character. We show advantage of our groupoids over known ones.
The Kähler quotient of a complex reductive Lie group relative to the conjugation action carries a complex algebraic stratified Kähler structure which reflects the geometry of the group. For the group SL(n,ℂ), we interpret the resulting singular Poisson-Kähler geometry of the quotient in terms of complex discriminant varieties and variants thereof.
We study the existence of a skew Killing spinor on 2- and 3-dimensional Riemannian spin manifolds. We establish the integrability conditions and prove that these spinor fields correspond to twistor spinors in the two dimensional case while, up to a conformal change of the metric, they correspond to parallel spinors in the three dimensional case.
We study Legendre and slant curves for Bianchi-Cartan-Vranceanu metrics. These curves are characterized through the scalar product between the normal at the curve and the vertical vector field and in the helix case they have a proper (non-harmonic) mean curvature vector field. The general expression of the curvature and torsion of these curves and the associated Lancret invariant (for the slant case) are computed as well as the corresponding variant for some particular cases. The slant (particularly...