2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147096In this paper we present a formula which relates the Donaldson invariants of a 4-manifold X with the Donaldson invariants of its blowup X#-CP(2). This blow-up formula is independent of X and involves sigma-functions associated to a naturally arising elliptic function. This, the final version, corrects some earlier misconceptions regarding signs.16 pages, AMS-LaTeXAlgebraic Geometrytext