An overlapping additive Schwarz preconditioner for boundary element approximations to the Laplace screen and Lamé crack problems

We study a two-level overlapping additive Schwarz preconditioner for the h-version of the Galerkin boundary element method when used to solve hypersingular integral equations of the first kind on an open surface in These integral equations result from Neumann problems for the Laplace and Lamé equations in the exterior of the surface. We prove that the condition number of the preconditioned system is bounded by O(1 + log2(H/δ)), where H denotes the diameter of the subdomains and δ the size of the overlap.