2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/70592We consider equations of the form Bf=g, where B is a Galois connection between lattices of functions. This includes the case where B is the Legendre-Fenchel transform, or more generally a Moreau conjugacy. We characterise the existence and uniqueness of a solution f in terms of generalised subdifferentials. This extends a theorem of Vorobyev and Zimmermann, relating solutions of max-plus linear equations and set coverings. We give various illustrations.33 pages, 2 Postscript figures; Acknowledgement addedFunctional Analysis06A15 (Primary), 52A01, 44A05 (Secondary)text