Abstract
The analysis of the accuracy of the aposteriori error estimation procedure for finite‐element solutions is presented. The function Y — y is used as an aposteriori error estimator, here y ∈ S 0 1,Δ is the finite‐element solution of the given problem and Y ∈ S 0 2,Δis the high order solution of the same problem. The second order accuracy is proved for this error estimator in the L 2, H 1 and L8 norms. Results of numerical experiments are presented.