2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59939The holonomic rank of the A-hypergeometric system H_A(β) is shown to depend on the parameter vector βwhen the underlying toric ideal I_A is a non Cohen Macaulay codimension 2 toric ideal. The set of exceptional parameters is usually infinite.24 pagesCombinatoricsAlgebraic Geometrytext