Local determination of conductivity at the boundary from the Dirichlet-to-Neumann map

We consider the problem of determining the conductivity of an isotropic, st atic conductive medium from the measurements of the electric potential on t he boundary and the corresponding current flux across that boundary, that i s, from the Dirichlet-to-Neumann map. Under some local regularity assumptio ns on the conductivity and on the boundary, we give a formula for reconstru cting pointwisely the conductivity and its derivatives on the boundary from the localized Dirichlet-to-Neumann map.