Decay of the relative energy error (5.1) in the two-level additive Schwarz method (Algorithm 1) for the |$p$|-Laplacian problem (2.1) (⁠|$p = 20$|⁠). Parameters |$h$|⁠, |$H$| and |$\delta $| stand for the characteristic element size, subdomain size and overlapping width among subdomains, respectively (⁠|$H/h = 2^{3}$|⁠).