“…Superconvergence has also been employed by the mesh refinement and adaptivity [48,51] to yield a posterior error estimator [1,4,8,52,53]. There has been a variety of research work in superconvergence based on finite difference methods [9,10], finite element methods [2,3,4,5,39,54,55], discontinuous Galerkin methods [6], hybridized discontinuous Galerkin methods [25], smoothed finite element methods [24], and weak Galerkin finite element methods [11,22,23,20,34,37].…”