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New York Journal of Mathematics
Volume 32 (2026), 691-718

  

Ondrej Chwiedziuk, Matej Dolezalek, Emma Pechouckova, Zdenek Pezlar, Om Prakash, Giuliano Romeo, Anna Ruzickova, and Mikulas Zindulka

Representing rational integers by generalized quadratic forms over quadratic fields

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Published: May 3, 2026.
Keywords: Generalized quadratic form, universal quadratic form, Hermitian form, real quadratic field.
Subject [2010]: 11E12, 11E16, 11E20, 11E25, 11E39, 11R11, 11R80.

Abstract
We investigate generalized quadratic forms with values in the set of rational integers over quadratic fields. We characterize the real quadratic fields which admit a positive definite binary generalized form of this type representing every positive integer. We also show that there are only finitely many such fields where a ternary generalized form with these properties exists.

Acknowledgements

We acknowledge support by Czech Science Foundation (GACR) grant 26-20514S, and Charles University programmes PRIMUS/24/SCI/010 and UNCE/24/SCI/022, and GAUK projects 134824 and 236225.


Author information

Ondrej Chwiedziuk
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

ondrachwiedziuk@gmail.com

Matej Dolezalek
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

matej@gimli.ms.mff.cuni.cz

Emma Pechouckova
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

emma.pechouckova@gmail.com

Zdenek Pezlar
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

zdendapezlar@seznam.cz

Om Prakash
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

omprakash@ksom.res.in

Giuliano Romeo
Department of Mathematical Sciences "Giuseppe Luigi Lagrange"
Politecnico di Torino, Turin, Italy

giuliano.romeo@polito.it

Anna Ruzickova
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

anna.ruzickova.13@gmail.com

Mikulas Zindulka
Charles University
Faculty of Mathematics and Physics, Department of Algebra
Sokolovska 83, 186 75 Praha 8, Czech Republic

mikulas.zindulka@matfyz.cuni.cz