2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147164Results in the preliminary version have been strengthed. In addition, Batyrev's conjectural formula for quantum cohomology of projective bundles associated to direct sum of line bundles over $\Pee^n$ is partially verified.AMS-TEX Version 2.1Algebraic Geometry14J60text