2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/124749A subvariety of a complex projective space has a well-known dual variety, which is the set of its tangent hyperplanes. The purpose of this paper is to generalise this notion for a subvariety of a quite general partial flag variety. A similar biduality theorem is proved, and the dual varieties of Schubert varieties are described.38 pagesAlgebraic Geometry14N99, 14L35, 14L40text