2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/77713We extend the notion of basic classes (for the Donaldson invariants) to 4-manifolds with $b^+>1$ which are (potentially) not of simple type or satisfy $b_1 >0$. We also give a structure theorem for the Donaldson invariants of 4-manifolds with $b^+>1$, $b_1>0$ and of strong simple type.13 pages, Latex2eDifferential Geometry58D27; 57R57text