Special Session 87: Mathematical Insights into Phase-Field Models

Optimal Control of the Fidelity Coefficient in Cahn--Hilliard Inpainting Models
Cecilia Cavaterra
University of Milan
Italy
Co-Author(s):    Elena Beretta, Matteo Fornoni, Maurizio Grasselli
Abstract:
We study an optimal control problem for a Cahn--Hilliard-type inpainting model, as originally proposed by Bertozzi et al. The model employs a linear reaction term, weighted by a fidelity coefficient, to restore a damaged image within a fixed subdomain. To ensure that the order parameter remains within the physically relevant range $[0,1]$, we employ a singular potential. We formulate a cost functional that accounts for the magnitude of the fidelity coefficient and analyze the resulting control-to-state operator. After proving the existence of optimal controls, we derive first-order optimality conditions and, under suitable assumptions, establish second-order optimality conditions.