Symplectic representatives in higher dimensions

Determine whether a cohomology class a\in H^2(M,\mathbb{R}) satisfying a^m\neq 0 on a closed almost complex manifold (M,J) of dimension 2m>4 can be represented by a symplectic form.

Background

The paper considers the fundamental symplectic-topology problem of deciding when a prescribed degree-two cohomology class on an even-dimensional manifold admits a symplectic representative. For a closed almost complex manifold of dimension 2m, the paper identifies the existence of an almost complex structure and the nonvanishing condition am\neq 0 as necessary conditions.

Although four-dimensional counterexamples are known through Seiberg–Witten theory, the paper states that the corresponding existence problem in dimensions higher than four remains unresolved. The proposed higher-dimensional gauge-theoretic equations are motivated in part by the goal of producing obstructions to compatible symplectic forms.

References

In higher dimensions the existence problem is completely open.

Gauge theory and symplectic structures  (2609.02699 - Ghosh, 2 Sep 2026) in Section 1, Introduction, subsection “Background”