Let $H_{\mathbb Z}$ be a free abelian group of finite rank, let $Q$ be a polarization of weight $k$, and fix Hodge numbers $(h^{p,k-p})_p$. Let
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\begin{align*}
H_{\mathbb C}:=H_{\mathbb Z}\otimes_{\mathbb Z}\mathbb C
\end{align*}
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and let $D$ be the classifying space of $Q$-polarized Hodge structures on $H_{\mathbb C}$ with the prescribed Hodge numbers, equipped with its invariant Hodge metric. Fix $F\in D$, and let
be the associated [Hodge decomposition](/theorems/2745).
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Let $\mathfrak g_{\mathbb C}\subset \operatorname{End}_{\mathbb C}(H_{\mathbb C})$ be the complex [Lie algebra](/page/Lie%20Algebra) of $Q$-infinitesimal automorphisms, and let
For $0\ne \xi\in \mathfrak g_F^{-1,1}$, let $\xi^*$ denote the adjoint of $\xi$ with respect to the positive definite Hodge metric on $H_{\mathbb C}$, let $\|\cdot\|_F$ denote the induced Hodge-metric norm on $\mathfrak g_{\mathbb C}$, and let $K_D(F,\xi)$ denote the holomorphic sectional curvature of $D$ along the complex line $\mathbb C\xi\subset T_FD$, using the Griffiths-Schmid curvature normalization. Then