The rationality problem for multinorm one tori, II
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866918426419658752 |
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| author | Hasegawa, Sumito Kanai, Kazuki Oki, Yasuhiro |
| author_facet | Hasegawa, Sumito Kanai, Kazuki Oki, Yasuhiro |
| contents | We investigate the stable and retract rationality of multinorm one tori associated to finite {é}tale algebras. Our results are organized according to the greatest common divisor $d$ of the degrees of the factors. We show that these tori are stably rational for $d=1$, and obtain a criterion for retract rationality that can be attributed to our previous results. For $d>1$, we provide sufficient conditions for the failure of retract rationality. We further generalize results of Endo--Miyata (1975) and Endo (2011) by giving an equivalent condition for multinorm one tori to be stably rational under the assumption that they split over Galois extensions with Galois groups in which all Sylow subgroups are cyclic. A similar result also holds when they split over dihedral Galois extensions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_02848 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | The rationality problem for multinorm one tori, II Hasegawa, Sumito Kanai, Kazuki Oki, Yasuhiro Algebraic Geometry Rings and Algebras 11E72, 12F20, 14E08, 20C10, 20G15 We investigate the stable and retract rationality of multinorm one tori associated to finite {é}tale algebras. Our results are organized according to the greatest common divisor $d$ of the degrees of the factors. We show that these tori are stably rational for $d=1$, and obtain a criterion for retract rationality that can be attributed to our previous results. For $d>1$, we provide sufficient conditions for the failure of retract rationality. We further generalize results of Endo--Miyata (1975) and Endo (2011) by giving an equivalent condition for multinorm one tori to be stably rational under the assumption that they split over Galois extensions with Galois groups in which all Sylow subgroups are cyclic. A similar result also holds when they split over dihedral Galois extensions. |
| title | The rationality problem for multinorm one tori, II |
| topic | Algebraic Geometry Rings and Algebras 11E72, 12F20, 14E08, 20C10, 20G15 |
| url | https://arxiv.org/abs/2604.02848 |