26 citations · 77 across the 19 of their papers we have counts for
6 papers · 1 filter
The twistor discriminant locus of the Fermat cubic
John Armstrong
We consider the discriminant locus of the Fermat cubic under the twistor fibration . We show that it has a conformal symmetry group of order and use…
Curvature of Hessian Manfiolds
Shun-ichi Amari, John Armstrong
We prove that, in dimensions greater than 2, the generic metric is not a Hessian metric and find a curvature condition on Hessian metrics in dimensions greater than 3. In particula…
Twistor Topology of the Fermat Cubic
John Armstrong, Simon Salamon
We describe topologically the discriminant locus of a smooth cubic surface in the complex projective space that contains 5 fibres of the projection ${\mathbb{CP}}…
Twistor lines on cubic surfaces
John Armstrong, Massimiliano Povero, Simon Salamon
It is shown that there exist non-singular cubic surfaces in CP^3 containing 5 twistor lines. This is the maximum number of twistor fibres that a non-singular cubic can contain. Cub…
Local models and integrability of certain almost Kahler 4-manifolds
Vestislav Apostolov, John Armstrong, Tedi Draghici
We classify, up to a local isometry, all non-Kahler almost Kahler 4-manifolds for which the fundamental 2-form is an eigenform of the Weyl tensor, and whose Ricci tensor is invaria…
Local rigidity of certain classes of almost Kahler 4-manifolds
Vestislav Apostolov, John Armstrong, Tedi Draghici
We show that any non-Kahler, almost Kahler 4-manifold for which both the Ricci and the Weyl curvatures have the same algebraic symmetries as they have for a Kahler metric is locall…