“…Based on certain localization techniques, the works [8,9,15,16,21], for instance, give suitable error estimators μ 2 = E∈E μ (E) 2 which satisfy η μ , but whose contributions μ (E), at least heuristically, measure the local error. Moreover, based on recent results from [5], a compound error estimator ρ which additionally controls data oscillations, is used for all problem settings discussed in this paper.…”