2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/96167We prove the version of Knebusch's Norm principle for simple extensions of (semi-)local rings. As an application we prove the Grothedieck-Serre's conjecture on principal homogeneous spaces for the split case of the spinor group.10 pages, using XYPICRings and AlgebrasCommutative AlgebraAlgebraic Geometry11E08text