Universal Two-Level Overlapping Schwarz Preconditioners for Efficient Solving of High-Order Elliptic Problems

The paper proposes a novel universal construction of two-level overlapping Schwarz preconditioners for 2mth-order elliptic boundary value problems, where m is a positive integer. The coarse space construction can be applied to any finite element discretization for any m that satisfies some common assumptions, ensuring scalable convergence rates.