Localized pointwise a posteriori error estimates for gradients of piecewise linear finite element approximations to second-order quasilinear elliptic problems Academic Article uri icon


  • Two types of pointwise a posteriori error estimates are presented for gradients of finite element approximations of second-order quasilinear elliptic Dirichlet boundary value problems over convex polyhedral domains Q in space dimension n 2. We first give a residual estimator which is equivalent to (u - uh)L () up to higher-order terms. The second type of residual estimator is designed to control (u - uh) locally over any subdomain of . It is a novel a posteriori counterpart to the localized or weighted a priori estimates of [Sch98]. This estimator is shown to be equivalent (up to higher-order terms) to the error measured in a weighted global norm which depends on the subdomain of interest. All estimates are proved for general shape-regular meshes which may be highly graded and unstructured. The constants in the estimates depend on the unknown solution u in the nonlinear case, but in a fashion which places minimal restrictions on the regularity of u. 2006 Society for Industrial and Applied Mathematics.

published proceedings

  • SIAM Journal on Numerical Analysis

author list (cited authors)

  • Demlow, A.

citation count

  • 15

complete list of authors

  • Demlow, Alan

publication date

  • January 2006