Identification and Control

The articles cover new developments in control theory and inverse problems. First, the problem of Calderón, which consists of determining a conductivity appearing in an elliptic equation from excitation and measurements on a part of the boundary of the domain, is studied. Second, an introduction to the mathematical analysis of inverse spectral problems of Borg- Levinson type is presented. Third, the control of multi-component systems of wave equations, focusing on the notion of simultaneous control (using the same control scheme in all components of the system at hand) and indirect control (using a single control for a system consisting of two components), is presented. Last, the study of the cost of control for parabolic systems, the finite time stabilization of hyperbolic control systems by boundary feedback laws, and image reconstruction by data assimilation are addressed.