Quaternion Hermitian Planes

Some Remarks on Quaternion-hermitian Manifolds

Nearly-quaternionic KK ahler manifolds of dimension at least 8 are shown to be quaternionic KK ahler. Restrictions on the covariant derivative of the fundamental four-form of a semi-quaternionic KK ahler are also found.

Curvature of Almost Quaternion- Hermitian Manifolds

We study the decomposition of the Riemannian curvature R tensor of an almost quaternion-Hermitian manifold under the action of its structure group Sp(n)Sp(1). Using the minimal connection, we show that most components are determined by the intrinsic torsion ξ and its covariant derivative ∇̃ξ and determine relations between the decompositions of ξ ⊗ ξ, ∇̃ξ and R. We pay particular attention to the...

Small Zeros of Hermitian Forms over a Quaternion Algebra

Let D be a positive definite quaternion algebra over a totally real number field K, F (X, Y ) a hermitian form in 2N variables over D, and Z a right D-vector space which is isotropic with respect to F . We prove the existence of a small-height basis for Z over D, such that F (X, X) vanishes at each of the basis vectors. This constitutes a non-commutative analogue of a theorem of Vaaler [19], an...

Realization of Hermitian Symmetric Spaces as Generalized Half-planes

Ela Extreme Ranks of (skew-)hermitian Solutions to a Quaternion Matrix Equation∗

The extreme ranks, i.e., the maximal and minimal ranks, are established for the general Hermitian solution as well as the general skew-Hermitian solution to the classical matrix equation AXA +BY B = C over the quaternion algebra. Also given in this paper are the formulas of extreme ranks of real matrices Xi, Yi, i = 1, · · · , 4, in a pair (skew-)Hermitian solution X = X1 + X2i + X3j + X4k, Y =...