2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/228We study each of the 16 types of complete intersection Calabi-Yau threefolds in projective n-space times the projective line, for various n, and prove existence of isolated rational curves of bidegree (d,0) for all positive integers d on a general threefold of each of these types. As a corollary we find isolated rational curves in all degrees on a general CICY of each of the 5 possible types in usual projective n-space.Some changes that were made in the published journal version are here incorporated in the web versionAlgebraic Geometry14J30 (Primary) 14J28, 14H45 (Secondary)text