High Quality Content by WIKIPEDIA articles! In mathematics, a Kähler manifold is a manifold with unitary structure (a U(n)-structure) satisfying an integrability condition. In particular, it is a Riemannian manifold, a complex manifold, and a symplectic manifold, with these three structures all mutually compatible.Without any integrability conditions, the analogous notion is an almost Hermitian manifold. If the Sp-structure is integrable (but the complex structure need not be), the notion is an almost Kähler manifold; if the complex structure is integrable (but the Sp-structure need not be), the notion is a Hermitian manifold.