Determination of period matrix of double of surface with boundary via its DN map
Dmitrii Korikov
TL;DR
The paper tackles the problem of recovering the conformal class of a surface with boundary from its Dirichlet-to-Neumann map by passing to the Schottky double and extracting the $b$-period matrix $\mathbb{B}$, which uniquely encodes the double’s conformal structure via the Torelli theorem. It presents a concrete four-step algorithm that starts from boundary data of harmonic normal fields, enforces integer-period conditions for Abelian differentials, constructs a canonical dual basis in the normal space, and computes the period matrices of the base surface and its double; the entire process hinges on the Hilbert transform, Abelian differentials, and canonical homology bases. The authors further develop implementation details to handle noisy DN data, proving that the resulting $b$-period matrix $\mathbb{B}'$ satisfies $\|\mathbb{B}'-\mathbb{B}\|=O(\varepsilon)$ under a small noise bound $\varepsilon$, thereby establishing stability of the reconstruction. Overall, the work reduces the infinite-dimensional EIT problem to finite-dimensional coordinates in the Siegel space via $\mathbb{B}$, enabling robust conformal-invariant characterization and potential numerical visualization of the unknown surface from boundary measurements.
Abstract
As is well-known, a conformal class of a surface $M$ with boundary $Γ$ is determined by its DN map $Λ$. In the paper, the algorithm for determination of the $b$-period matrix $\mathbb{B}$ of the (Schottky) double of surface with boundary via $Λ$ is presented. Due to the Torelli theorem, $\mathbb{B}$ contains all information on the conformal class of $M$ except the proper way of attaching $Γ$ to it.
