Pfister's subform theorem for reduced special groups

Zusammenfassung

Pfister's subform theorem is an essential result in the theory of quadratic forms, but its proof uses transcendental field extensions which have no equivalent in the axiomatic theory. We present here a proof of this result for reduced special groups/spaces of orderings which avoids this difficulty. (C) 2003 Elsevier B.V. All rights reserved.