2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/96288The computation of the step scaling function for the finite size mass-gap in the O(N) sigma model at large N is reviewed. Practically exact nonperturbative results become available for both finite and vanishing lattice spacing. We use them as a testbed to investigate standard procedures of continuum extrapolation in lattice field theory.6 pages, 2 figures, contribution of U.W. to Lat05, DublinHigh Energy Physics - Latticetext