2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147103We deduce some formulas for the spin invariants of the connected sum of an arbitrary 4-manifold X, b^+ _2(X) > 0 $ with $\overline {CP^2}$ in terms of the spin invariants of $X$ and apply this to prove the Van de Ven conjecture.17 pages. AmS-TeX-Version 2.1. A new reference is added (pp.1,15)Algebraic Geometrytext