Stable determination of a simple metric, a covector field and a   potential from the hyperbolic Dirichlet-to-Neumann map
  Let (M,g) be a compact Riemmanian manifold with non-empty boundary. Consider the second order hyperbolic initial-boundary value problem (\delta_t^2 + P(x,D))u = 0 in (0,T) x M, u(0,x) = \delta_t u(0,x) = 0 for x in M, u(t,x) = f(t,x) on (0,T) x \delta M; where P(x,D) is a first-order perturbation of the Laplace-Beltrami operator on (M,g). Let b and q be the covector field and the potential of P(x,D), respectively, in M. We prove H\"older type stability estimates near generic simple Riemannian metrics for the inverse problem of recovering g, b, and q from the hyperbolic Dirichlet-to-Neumann(DN) map associated, f maps to <\nu,u>_g - i<\nu,b>_g u|_{\delta M x [0,T]} where v is unit conormal to the boundary, modulo a class of transformations that fixed the DN map. 
Carlos Montalto
math.AP math-ph math.MP math.SP