2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/152927Assuming an inaccessible cardinal kappa, there is a generic extension in which MA + 2^{aleph_0} = kappa holds and the reals have a Delta^2_1 well-ordering.LogicMartin's Axiom and Delta^2_1 well-ordering of the realstext