andrew.dolphin@uclouvain.be

Submission: 2013, Aug 7

We show that over a field of characteristic 2 a central simple algebra with orthogonal involution that decomposes into a product of quaternion algebras with involution is either anisotropic or metabolic. We use this to define an invariant of such orthogonal involutions in characteristic 2 that completely determines the isotropy behaviour of the involution. We also give an example of a non-totally decomposable algebra with orthogonal involution that becomes totally decomposable over every splitting field of the algebra.

2010 Mathematics Subject Classification: 11E39, 11E81, 12F05, 12F10

Keywords and Phrases: Central simple algebras; quaternion algebras; involutions; Pfister forms; characteristic two, Pfister Factor Conjecture.

Full text: dvi.gz 37 k, dvi 88 k, ps.gz 714 k, pdf.gz 184 k, pdf 203 k.

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