An inverse problem originating from magnetohydrodynamics, III. Domains with corners of arbitrary angles

We seek to identify the non-linearity of the semilinear elliptic equation, ▵u=−f(u) ≤ 0, from boundary measurements of the normal flux corresponding to homogeneous Dirichlet data. The possibility of such identification depends crucially on the shape of the domain. In this paper we prove that identification of an analytic function f is (generically) possible if the domain has a proper corner. This result significantly extends an earlier result obtained in [2], by almost entirely eliminating the restrictions imposed on the size of the angle of the corner.