A stronger notion is a geometrically formal manifold, a manifold on which all wedge products of harmonic forms are harmonic.[2]
Referencesedit
^Sullivan, Dennis (1975). "Differential forms and the topology of manifolds". Manifolds—Tokyo 1973 (Proc. Internat. Conf., Tokyo, 1973). Tokyo: University of Tokyo Press. pp. 37–49. MR 0370611. Zbl 0319.58005.