  For elliptic interface problems, this paper studies residual-based a
posteriori error estimations for various finite element approximations. For the
conforming and the Raviart-Thomas mixed elements in two-dimension and for the
Crouzeix-Raviart nonconforming and the discontinuous Galerkin elements in both
two- and three-dimensions, the global reliability bounds are established with
constants independent of the jump of the diffusion coefficient. Moreover, we
obtain these estimates with no assumption on the distribution of the diffusion
coefficient.
