A holomorphic differential form of type satisfies . The adjoint lowers antiholomorphic degree, so as well. Therefore .
The Kähler Laplacian identity gives . Compactness lets us use the identity for the Hodge Laplacian:
Both terms are nonnegative, so
This proves that holomorphic forms on a compact Kähler manifold are closed. The original PDF uses and ; the extra symbols in the local TeX superscripts are transcription errors.