2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/128067We answer a question of Shelah by showing that it is consistent that every set of ordinals of cofinality omega_1 in I[omega_2] is nonstationary if and only if it is consistent that that there is a kappa^+ Mahlo cardinal kappa.version 4 of the paper has been extensively revised in response to the referee report from TAMS. I expect it to appear in TAMSLogic03E35text