Almost-quaternion $(m-1)$-substructures on $S\sp{4m-3}$

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...

m at h . SG ] 3 A ug 1 99 8 Almost complex structures on S 2 ×

In this note we investigate the structure of the space J of smooth almost complex structures on S 2 × S 2 that are compatible with some symplectic form. This space has a natural stratification that changes as the cohomology class of the form changes and whose properties are very closely connected to the topol-ogy of the group of symplectomorphisms of S 2 × S 2. By globalizing standard gluing co...

M ar 2 00 3 ALMOST NORMAL HEEGAARD SURFACES

We present a new and shorter proof of Stocking's result that any strongly irreducible Heegaard surface of a closed orientable triangulated 3– manifold is isotopic to an almost normal surface. We also reprove a result of Jaco and Rubinstein on normal spheres.

On Possible Non - Homeomorphic Substructures of the Real Line 3

ar X iv : 1 10 3 . 25 44 v 1 [ cs . I T ] 1 3 M ar 2 01 1 Almost - perfect secret sharing

Splitting a secret s between several participants, we generate (for each value of s) shares for all participants. The goal: authorized groups of participants should be able to reconstruct the secret but forbidden ones get no information about it. In this paper we introduce several notions of non-perfect secret sharing, where some small information leak is permitted. We study its relation to the...