The axiom of θ-holomorphic 2-planes in the almost Hermitian geometry

Grozjo Stanilov, Ognian Kassabov

The axiom of θ-holomorphic 2-planes is introduced. It is proved, that if an almost Hermitian manifold satisfies this axiom for a fixed θ, 0< θ< π/2, then it is a real space form.