Lipschitz Stability for the Inverse Conductivity Problem

We discuss the stability issue for Calder\uf3n's inverse conductivity problem, also known as Electrical Impedance Tomography. It is well known that this problem is severely ill-posed. In this paper we prove that if it is a-priori known that the conductivity is piecewise constant with a bounded number of unknown values, then a Lipschitz stability estimate holds