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Main Authors: Ouyang, Yi, Zhang, Chenhao
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.03277
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author Ouyang, Yi
Zhang, Chenhao
author_facet Ouyang, Yi
Zhang, Chenhao
contents In this paper, we establish a real closed analogue of Bertini's theorem. Let $R$ be a real closed field and $X$ a formally real integral algebraic variety over $R$. We show that if the zero locus of a nonzero global section $s$ of an invertible sheaf on $X$ has a formally real generic point, then $s$ does not change sign on $X$, and vice versa under certain conditions. As a consequence, we demonstrate that there exists a nonempty open subset of hypersurface sections preserving formal reality and integrality for quasi-projective varieties of dimension $\geq 2$ under these conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03277
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Generalized connectedness and Bertini-type theorems over real closed fields
Ouyang, Yi
Zhang, Chenhao
Algebraic Geometry
14P25, 12J15
In this paper, we establish a real closed analogue of Bertini's theorem. Let $R$ be a real closed field and $X$ a formally real integral algebraic variety over $R$. We show that if the zero locus of a nonzero global section $s$ of an invertible sheaf on $X$ has a formally real generic point, then $s$ does not change sign on $X$, and vice versa under certain conditions. As a consequence, we demonstrate that there exists a nonempty open subset of hypersurface sections preserving formal reality and integrality for quasi-projective varieties of dimension $\geq 2$ under these conditions.
title Generalized connectedness and Bertini-type theorems over real closed fields
topic Algebraic Geometry
14P25, 12J15
url https://arxiv.org/abs/2511.03277