Algebraic Geometry – Fujiki Class C with a Symplectic Structure

ag.algebraic-geometrycomplex-geometrykahler-manifoldssg.symplectic-geometry

Recall that a compact complex manifold $X$ is said to be in Fujiki class $\mathcal C$ if there is a proper modification $\mu:\tilde X\to X$ such that $\tilde X$ is a compact Kähler manifold. If $X$ admits a symplectic structure, i.e. $X$ carries a closed nondegenerate 2-form $\omega$, then is $X$
Kähler?

Best Answer

If $X'$ is a Mukai flop of a compact hyper-Kähler manifold $X$, then $X'$ is in Fujiki class $\mathcal{C}$ and carries a holomorphic symplectic form $\sigma$. Taking the real part or the imaginary part of $\sigma$ gives a symplectic form on $X'$.

There exist however Mukai flops which are not Kähler, see e.g. this paper of Yoshioka, Section 4.4.

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