2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/193840We show that all IIB supergravity backgrounds which admit more than 28 Killing spinors are maximally supersymmetric. In particular, we find that for all N>28 backgrounds the supercovariant curvature vanishes, and that the quotients of maximally supersymmetric backgrounds either preserve all 32 or N<29 supersymmetries.27 pagesHigh Energy Physics - Theorytext