2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/153137We show that the consistency strength of the system NFUB, a variant of Quine's "New Foundations" recently introduced by Randall Holmes, is precisely that of [ZFC - Power Set] + "There is a weakly compact cardinal''. This is a preliminary draft of the paper. Nevertheless, it contains a complete proof.Logictext