2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/137034We present some theorems and algorithms for calculating perpendicular categories and locally semi-simple decompositions. We implemented a computer program {\sc TETIVA} based on these algorithms and we offer this program for everybody's use.15 pagesRepresentation TheoryAlgebraic Geometry14L30;16G20text