“…We mention multigrid preconditioners, [AG17] based on uniformly refined mesh hierarchies and operator preconditioning, [Hip06,GSUT19,SvV19], which requires one to realize an operator of the opposite order. Another, classical technique is the framework of additive Schwarz preconditioners, analyzed in a BPX-setting with Fourier techniques in [BLN19]. In the present work, we also adopt the additive Schwarz framework and show that, also in the presence of adaptively refined meshes, multilevel diagonal scaling leads to uniformly bounded condition numbers for the integral fractional Laplacian.…”