“…It is noteworthy, however, that the use of dual solutions in a-posteriori error estimates, which forms the basis of goal-oriented error estimation, had already been pursued before by Johnson, Eriksson and Hansbo [10,21,22]. Goal-oriented adaptivity has been successfully applied to a wide variety of problems including compressible and incompressible flow problems [17,31,32], elasticity and plasticity [37,33,34], variational inequalities [38], fluid-structure interaction [45,13,36,6], free-boundary problems [46,47], phase-field models [42,44], and kinetic equations [19]. This overview is in fact far from exhaustive, and many more applications and contributions can be found in the literature.…”