queguin@math.univ-paris13.fr
Submission: 2008, Feb 8
We use the fact that a projective half-spin representation of $Spin_{12}$ has an open orbit to generalize Pfister's result on quadratic forms of dimension 12 in the third power of the fundamental ideal to orthogonal involutions.
2000 Mathematics Subject Classification: 20G15; 16W10; 11E04
Keywords and Phrases: Algebraic groups; Orthogonal involutions ; Quadratic forms
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