Low-rank approximation of elliptic boundary value problems with   high-contrast coefficients
  We analyze the convergence of degenerate approximations to Green's function of elliptic boundary value problems with high-contrast coefficients. It is shown that the convergence is independent of the contrast if the error is measured with respect to suitable norms. This lays ground to fast methods (so-called hierarchical matrix approximations) which do not have to be adapted to the coefficients. 
M. Bebendorf
math.NA