Maximum-norm a posteriori error bounds for an extrapolated Euler/finite element discretisation of parabolic equations

A class of linear parabolic equations are considered. We give a posteriori error estimates in the maximum norm for a method that comprises extrapolation applied to the backward Euler method in time and finite element discretisations in space. We use the idea of elliptic reconstructions and certain bounds for the Green’s function of the parabolic operator.