(3+3+2) Warped-Like Product Manifolds With Spin(7) Holonomy.

      Аннотация: In the theory of Riemannian holonomy groups there are two exceptional cases, the holonomy group G_2 in 7-dimensional and the holonomy group Spin(7) in 8-dimensional manifolds. In the present work, we investigate the structure of Riemannian manifolds whose holonomy group is a subgroup of Spin(7) for a special case. Manifolds with Spin(7) holonomy are characterized by the existence of a 4-form, called the Bonan form (Cayley form or Fundamental form), which is self-dual in the Hodge sense, Spin(7) invariant and closed. We review two methods for the construction of the Bonan form, based on the octonionic multiplication and the triple vector cross products on octonions. Here we define “(3+3+2) warped-like product manifolds" as a generalization of multiply warped product manifolds, by allowing the fiber metric to be non block diagonal. In this thesis we prove that the fibre spaces of (3+3+2) warped-like product manifolds are isometric to 3-sphere under some global assumptions.

Ключевые слова: Spin(7) manifolds, Holonomy, warped and multiply warped product manifold, warped-like product manifolds