2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/229106In this paper, we prove some foundational results on the deformation theory of E-infinity ring spectra.74 pages. Revised: 5/4/09. Some material rewritten to apply to more general operads, some material on the Goodwillie calculus has been removed (and given its own paper)Algebraic TopologyCategory Theory18G55text