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pro vyhledávání: '"Hoffmann, Detlev W."'
Autor:
Hoffmann, Detlev W.
We give examples of quaternion and octonion division algebras over a field $F$ of characteristic $2$ that split over a purely inseparable extension $E$ of $F$ of degree $\geq 4$ but that do not split over any subextension of $F$ inside $E$ of lower e
Externí odkaz:
http://arxiv.org/abs/2012.09644
Autor:
Hoffmann, Detlev W.
We say that a field extension $L/F$ has the descent property for isometry (resp. similarity) of quadratic or symmetric bilinear forms if any two forms defined over $F$ that become isometric (resp. similar) over $L$ are already isometric (resp. simila
Externí odkaz:
http://arxiv.org/abs/2006.04741
Autor:
Hoffmann, Detlev W.
Suppose a positive integer $n$ is written as a sum of squares of $m$ integers. What can one say about the value $T$ of the sum of these $m$ integers itself? Which $T$ can be obtained if one considers all possible representations of $n$ as a sum of sq
Externí odkaz:
http://arxiv.org/abs/1902.07109
Autor:
Hoffmann, Detlev W., Sobiech, Marco
Let $F$ be a field of characteristic $2$ and let $E/F$ be a field extension of degree $4$. We determine the kernel $W_q(E/F)$ of the restriction map $W_qF\to W_qE$ between the Witt groups of nondegenerate quadratic forms over $F$ and over $E$, comple
Externí odkaz:
http://arxiv.org/abs/1403.3064
Autor:
Hoffmann, Detlev W.
Let $F$ be a field of characteristic $2$ and let $K/F$ be a purely inseparable extension of exponent $1$. We show that the extension is excellent for quadratic forms. Using the excellence we recover and extend results by Aravire and Laghribi who comp
Externí odkaz:
http://arxiv.org/abs/1403.1802
Autor:
Hoffmann, Detlev W.
Let F be a field of characteristic different from 2. The u-invariant and the Hasse number of a field F are classical and important field invariants pertaining to quadratic forms. These invariants measure the suprema of dimensions of anisotropic forms
Externí odkaz:
http://arxiv.org/abs/1004.2483
Autor:
Hoffmann, Detlev W.
Publikováno v:
Proceedings of the American Mathematical Society, 2006 Mar 01. 134(3), 645-652.
Externí odkaz:
https://www.jstor.org/stable/4098410
Autor:
Hoffmann, Detlev W., Laghribi, Ahmed
Publikováno v:
Transactions of the American Mathematical Society, 2004 Oct 01. 356(10), 4019-4053.
Externí odkaz:
https://www.jstor.org/stable/3844972