 The method delivers a stable continuous approximation and projects the residual onto a broken polynomial space . This projection delivers a reliable error estimate that drives mesh refinement by minimizing a discrete energy norm  .
<coherence>  The method delivers a stable continuous approximation and projects the residual onto a broken polynomial space . This projection delivers a reliable error estimate that drives mesh refinement by minimizing a discrete energy norm  .
 The method delivers a stable continuous approximation and projects the residual onto a broken polynomial space , which is a robust error estimator to minimize the discrete energy norm .