Results 141 to 150 of about 474 (166)

GROUP ACTION ON THE DEFORMATIONS OF A FORMAL GROUP OVER THE RING OF WITT VECTORS

Nagoya Mathematical Journal, 2017
A recent result by the authors gives an explicit construction for a universal deformation of a formal group $\unicode[STIX]{x1D6F7}$ of finite height over a finite field $k$ . This provides in particular a parametrization of the set of deformations of $\unicode[STIX]
Demchenko, Oleg, Gurevich, Alexander
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Witt rings and the quaternion group

manuscripta mathematica, 1998
Let \(F\) be a formally real field having at most a finite number of orderings. This article examines the structure of the Witt ring of \(F\) and the maximal pro-2 Galois group of \(F\) in the case when \(F\) admits no quaternionic Galois extension. This extends earlier work of the author where the case of a field having at most one ordering and no ...
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Relations Between Witt Rings and Brauer Groups

1993
Let R be a commutative ring with unit element. To R we can associate the Witt ring W(R) which classifies the nondegenerate quadratic forms Q on finitely generated projective R-modules M and the Brauer group Br(R) which classifies the Azumaya algebras A over R, that is, A is a finitely generated projective R-module and, if A’ rev denotes the reversed ...
Jacques Helmstetter, Artibano Micali
openaire   +1 more source

Witt Groups of Affine Rings

1991
In this last chapter we consider Witt groups of the coordinate rings of some algebraic varieties, mainly real affine curves and surfaces.
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The Weil-Châtelet group, valuations, and the Witt ring

Mathematische Zeitschrift, 1999
For a field \(F\) of arbitrary characteristic the author introduces the notion of rigidity of a subset \(T\) of \(F^{*2}\) containing \(-1\) relative to an elliptic curve \(X\) with points of order two \(F\)-rational. Thus \(X\) is given by \(y^2 = f(x) = (x-e_1)(x-e_2)(x-e_3)\) where \(e_1,e_2,e_3 \in F\). \((T,X)\) is said to be rigid if whenever a \(
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Brauer Group Analogues of Results Relating the Witt Ring to Valuations and Galois Theory

Canadian Journal of Mathematics, 1995
AbstractLet F be a field of characteristic different from p containing a primitive p-th root of unity. This paper studies the cup product pairing Hl(F, p) x Hl(F, p) → H2(F, p) and its relationship to valuation theory and Galois theory. Sufficient conditions on the pairing which guarantee the existence of a valuation on the field are described.
Hwang, Yoon Sung, Jacob, Bill
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GALOIS MODULI OF PERIOD $p$ GROUP SCHEMES OVER A RING OF WITT VECTORS

Mathematics of the USSR-Izvestiya, 1988
Let k be a perfect field of characteristic p\(>0\), \(A=W(k)\) the ring of Witt vectors over k, K the quotient field of A and \(G=Gal(\bar K/K)\) the Galois group of the algebraic closure \(\bar K\) of K. Let C be the category of all finite commutative group schemes over A which are killed by the multiplication by p, and let MG(k) be the category of ...
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Witt Rings and Brauer Groups Under Multiquadratic Extensions, I

American Journal of Mathematics, 1983
Elman, Richard, Lam, T. Y., Tignol, J.-P., Wadsworth, Adrian R.   +3 more
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Witt rings of global function fields

Functiones Et Approximatio, Commentarii Mathematici, 2000
Alfred Czogała
exaly  

The Rings of Witt Vectors for Noncommutative Rings with Some Rich Structure

Communications in Algebra, 2010
Shushi Harashita
exaly