2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/169157In this note, we look at estimates for the scalar curvature k of a Riemannian manifold M which are related to spin^c Dirac operators: We show that one may not enlarge a Kaehler metric with positive Ricci curvature without making k smaller somewhere on M. We also give explicit upper bounds for min(k) for arbitrary Riemannian metrics on certain submanifolds of complex projective space. In certain cases, these estimates are sharp: we give examples where equality is obtained.19 pages, AmSTeXDifferential Geometry53C21 (Primary) 58G10, 53C55 (Secondary)text