7 citations · 21 across the 8 of their papers we have counts for
11 papers
Locally conformal SKT structures
Bachir Djebbar, Ana Cristina Ferreira, Anna Fino +1
A Hermitian metric on a complex manifold is called SKT (strong Kähler with torsion) if the Bismut torsion -form is closed. As the conformal generalization of the SKT conditi…
Non-existence of orthogonal complex structures on the round 6-sphere
Ana Cristina Ferreira
In this short note, we review the well-known result that there is no orthogonal complex structure on the 6-sphere with respect to the round metric.
Palais leaf-space manifolds and surfaces carrying holomorphic flows
Ana Cristina Ferreira, Julio C. Rebelo, Helena Reis
Starting from some remarkable singularities of holomorphic vector fields, we construct (open) complex surfaces over which the singularities in question are realized by complete vec…
Complete commuting vector fields and their singular points in dimension 2
Ana Cristina Ferreira, Julio C. Rebelo, Helena Reis
We classify degenerate singular points of $\C^2$-actions on complex surfaces.
Tangent Lie groups are Riemannian naturally reductive spaces
Ilka Agricola, Ana Cristina Ferreira
Given a compact Lie group with Lie algebra , we consider its tangent Lie group . In this short note, we prove that $T…
Dirichlet principal eigenvalue comparison theorems in geometry with torsion
Ana Cristina Ferreira, Isabel Salavessa
We describe min-max formulas for the principal eigenvalue of a -drift Laplacian defined by a vector field on a geodesic ball of a Riemannian manifold . Then we derive com…
Quaternionic Heisenberg groups as naturally reductive homogeneous spaces
Ilka Agricola, Ana Cristina Ferreira, Reinier Storm
In this note, we describe the geometry of the quaternionic Heisenberg groups from a Riemannian viewpoint. We show, in all dimensions, that they carry an almost -contact metric s…
The classification of naturally reductive homogeneous spaces in dimensions
Ilka Agricola, Ana Cristina Ferreira, Thomas Friedrich
We present a new method for classifying naturally reductive homogeneous spaces -- i.\,e.~homogeneous Riemannian manifolds admitting a metric connection with skew torsion that has p…
Einstein manifolds with skew torsion
Ilka Agricola, Ana Cristina Ferreira
This paper is devoted to the first systematic investigation of manifolds that are Einstein for a connection with skew symmetric torsion. We derive the Einstein equation from a vari…
Einstein four-manifolds with skew torsion
Ana Cristina Ferreira
We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian manifolds of dimension four. We prove an analogue of the Hitchin-Thorpe inequality and…
A vanishing theorem in twisted de Rham cohomology
Ana Cristina Ferreira
We prove a vanishing theorem for the twisted de Rham cohomology of a compact manifold.