Let $\mathcal X$ be a smooth complex manifold of dimension $n+1$. We say $\mathcal X \to ∆$ is a large complex structure limit if and only if it’s maximal unipotent degeneration .

$T: H^n(\mathcal X_s, \mathbb Z) → H^n(\mathcal X_s, \mathbb Z)$ is maximal quasi-unipotent, i.e.,

$∃s$ s.t. $(T^s − id)^{n+1} = 0$, $(T^s − id)^n\neq 0$

Here $T$ is the monodromy operator. Take $\mathcal X_s\cong X$ are Calabi-Yau varieties. We call $\mathcal X\to \Delta$ is the CY degeneration of $X$. This definition is due to the work of Griffiths–Landman–Grothendieck-Katz and P.Deligne

Let $X ⊂ \mathbb P^n$ be a CY variety and there exists large complex structure degeneration of $X$ then when the limit $\mathcal X_0$ is unique?

For example the uniqueness of the $\mathcal X_0$ may not be true if $X$ is complete intersection in toric orbifold.