It is shown that in dimension 4 there are no almost Kaehler manifolds of constant curvature unless the constant is 0, in which case the manifold is Kaehlerian. This was previously shown in dimensions ≥ 8 \geq 8 by Z. Olszak and remains open in dimension 6.
Erhan AtaH. Hilmi HacısalihoğluYusuf Yaylı