Small zeros of quadratic forms over the algebraic closure of Q

dc.creatorFukshansky, Lenny
dc.date2005-12-06
dc.date2007-03-21
dc.date.accessioned2026-07-07T09:57:11Z
dc.date.available2026-07-07T09:57:11Z
dc.descriptionLet $N \geq 2$ be an integer, $F$ a quadratic form in $N$ variables over $\bar{\mathbb Q}$, and $Z \subseteq \bar{\mathbb Q}^N$ an $L$-dimensional subspace, $1 \leq L \leq N$. We prove the existence of a small-height maximal totally isotropic subspace of the bilinear space $(Z,F)$. This provides an analogue over $\bar{\mathbb Q}$ of a well-known theorem of Vaaler proved over number fields. We use our result to prove an effective version of Witt decomposition for a bilinear space over $\bar{\mathbb Q}$. We also include some related effective results on orthogonal decomposition and structure of isometries for a bilinear space over $\bar{\mathbb Q}$. This extends previous results of the author over number fields. All bounds on height are explicit.
dc.description17 pages; revised version per referee's request, in particular section 6 has been largely expanded; to appear in the International Journal of Number Theory
dc.identifierhttps://arxiv.org/abs/math/0512132
dc.identifierhttp://arxiv.org/abs/math/0512132
dc.identifierInternational Journal of Number Theory, vol. 4 no. 3 (2008), pg. 503-523
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/167250
dc.subjectNumber Theory
dc.subject11E12, 11G50, 11H55, 11D09
dc.titleSmall zeros of quadratic forms over the algebraic closure of Q
dc.typetext

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