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UNIRATIONALITY AND GEOMETRIC UNIRATIONALITY FOR HYPERSURFACES IN POSITIVE CHARACTERISTICS

Part of: Special varieties Surfaces and higher-dimensional varieties Arithmetic problems. Diophantine geometry

Published online by Cambridge University Press:  08 March 2021

Keiji Oguiso  and
Stefan Schröer Open the ORCID record for Stefan Schröer [Opens in a new window]
Keiji Oguiso
Affiliation:
Department of Mathematical Sciences, The University of Tokyo, Meguro Komaba 3-8-1, Tokyo, Japan, and National Center for Theoretical Sciences, Mathematics Division, National Taiwan University Taipei, Taiwan (oguiso@ms.u-tokyo.ac.jp)
Stefan Schröer
Affiliation:
Mathematisches Institut, Heinrich-Heine-Universität, 40204Düsseldorf, Germany (schroeer@math.uni-duesseldorf.de)
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Abstract

Building on work of Segre and Kollár on cubic hypersurfaces, we construct over imperfect fields of characteristic $p\geq 3$ particular hypersurfaces of degree p, which show that geometrically rational schemes that are regular and whose rational points are Zariski dense are not necessarily unirational. A likewise behavior holds for certain cubic surfaces in characteristic $p=2$ .

Keywords

Unirationalhypersurfacesimperfect fields

MSC classification

Primary: 14M20: Rational and unirational varieties
Secondary: 14J70: Hypersurfaces 14G05: Rational points 14J26: Rational and ruled surfaces 14G17: Positive characteristic ground fields
Type
Research Article
Information
Journal of the Institute of Mathematics of Jussieu , Volume 21 , Issue 5 , September 2022 , pp. 1831 - 1847
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Copyright
© The Author(s), 2021. Published by Cambridge University Press

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