  In this paper, we consider several geometric inverse problems for linear
elliptic systems. We prove uniqueness and stability results. In particular, we
show the way that the observation depends on the perturbations of the domain.
In some particular situations, this provides a strategy that could be used to
compute approximations to the solution of the inverse problem. In the proofs,
we use techniques related to (local) Carleman estimates and differentiation
with respect to the domain.
