990 research outputs found
Systems of symplectic forms on four-manifolds
We study almost Hermitian 4-manifolds with holonomy algebra, for the
canonical Hermitian connection, of dimension at most one. We show how
Riemannian 4-manifolds admitting five orthonormal symplectic forms fit therein
and classify them. In this set-up we also fully describe almost Kaehler
4-manifolds.Comment: Final version, to appear in Annali di SNS.added thm. 5.
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