Decomposing Centrally Symmetric Convex Polyhedral Surfaces into Parallelograms

Abstract: Let $\mathcal{M}<em>{2N}(δ_1, δ_2,\dots, δ_N)$ be the moduli space of centrally symmetric convex polyhedral surfaces with $2N$ labeled vertices and prescribed cone-deficits $δ_1$, $δ_2$, $\dots$, $δ_N$. We show that $\mathcal{M}</em>{2N}(δ<em>1, δ_2,\dots, δ_N)$ has the structure of a real hyperbolic manifold of dimension $2N-3$. When $N=4$ and $5$, we show that every surface in $\mathcal{M}</em>{2N}(δ_1, δ_2,\dots, δ_N)$ can be decomposed into at most $2\binom{2N-2}{2}$ parallelograms, and the decomposition is invariant under the antipodal map. Using the edge-lengths of these parallelograms as coordinates, we show that the moduli space of centrally symmetric polyhedral surfaces with $8$ unlabeled vertices and cone-deficits $\fracπ{2}$ is isometric to the quotient of a real hyperbolic regular ideal $5$-simplex by the dihedral group $D_6$.