6 papers
Decomposability of orthogonal involutions in degree 12
Anne Quéguiner-Mathieu, Jean-Pierre Tignol
A theorem of Pfister asserts that every -dimensional quadratic form with trivial discriminant and trivial Clifford invariant over a field of characteristic different from d…
The canonical quadratic pair on a Clifford algebra and triality
Andrew Dolphin, Anne Quéguiner-Mathieu
We define a canonical quadratic pair on the Clifford algebra of an algebra with quadratic pair over a field. This allows us to extend to the characteristic 2 case the notion of tri…
Orthogonal involutions on central simple algebras and function fields of Severi-Brauer varieties
Anne Quéguiner-Mathieu, Jean-Pierre Tignol
An orthogonal involution on a central simple algebra , after scalar extension to the function field of the Severi--Brauer variety of , is adjoint to a qu…
Critical varieties and motivic equivalence for algebras with involution
Charles De Clercq, Anne Quéguiner-Mathieu, Maksim Zhykhovich
Motivic equivalence for algebraic groups was recently introduced in [9], where a characterization of motivic equivalent groups in terms of higher Tits indexes is given. As a conseq…
Symplectic Involutions, quadratic pairs and function fields of conics
Andrew Dolphin, Anne Quéguiner-Mathieu
In this paper we study symplectic involutions and quadratic pairs that become hyperbolic over the function field of a conic. In particular, we classify them in degree 4 and deduce…
A generic characterization of direct summands for orthogonal involutions
Anne Quéguiner-Mathieu
The `transcendental methods' in the algebraic theory of quadratic forms are based on two major results, proved in the 60's by Cassels and Pfister, and known as the representation a…