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In this short note, we review the well-known result that there is no orthogonal complex structure on S 6 with respect to the round metric. [ABSTRACT FROM AUTHOR]

We show that Hopf hypersurfaces in complex projective space are constructed from half-dimensional totally complex submanifolds in complex 2-plane Grassmannian and Legendrian submanifolds in the twistor space. [ABSTRACT FROM AUTHOR]

A study of tensors on the quaternionic projective plane HP 2 arising from a stable 3-form on C 6 and an associated action of SU (3) is related to the existence of a holomorphic rank 3 vector bundle over CP 5 discovered by Horrocks. It also leads to the construction of SU (3) invariant Spin (7) structures on HP 2 , which are characterised in terms of associated 4-forms. [ABSTRACT FROM AUTHOR]

In this paper a bijective correspondence between superminimal surfaces of an oriented Riemannian 4-manifold and particular Lagrangian submanifolds of the twistor space over the 4-manifold is proven. More explicitly, for every superminimal surface a submanifold of the twistor space is constructed which is Lagrangian for all the natural almost Hermitian structures on the twistor space. The twistor fibration restricted to the constructed Lagrangian gives a circle bundle over the superminimal surface. Conversely, if a submanifold of the twistor space is Lagrangian for all the natural almost Hermitian structures, then the Lagrangian projects to a superminimal surface and is contained in the Lagrangian constructed from this surface. In particular this produces many Lagrangian submanifolds of the twistor spaces C P 3 and F 1 , 2 (C 3) with respect to both the Kähler structure as well as the nearly Kähler structure. Moreover, it is shown that these Lagrangian submanifolds are minimal submanifolds. [ABSTRACT FROM AUTHOR]

Donaldson-Friedman constructed anti-self-dual classes on K 3 # 3 CP 2 ‾ using twistor space. We show that some of these conformal classes have almost-Kähler representatives. [ABSTRACT FROM AUTHOR]

Space-like surfaces and time-like surfaces with zero mean curvature vector in oriented neutral 4-manifolds are isotropic and compatible with the orientations of the spaces if and only if their lifts to the space-like and the time-like twistor spaces respectively are horizontal. In neutral Kähler surfaces and paraKähler surfaces, complex curves and paracomplex curves respectively are such surfaces and characterized by one additional condition. In neutral 4-dimensional space forms, the holomorphic quartic differentials defined on such surfaces vanish. There exist time-like surfaces with zero mean curvature vector and zero holomorphic quartic differential which are not compatible with the orientations of the spaces and the conformal Gauss maps of time-like surfaces of Willmore type and their analogues give such surfaces. [ABSTRACT FROM AUTHOR]