3 papers
math.AG2026
The rationality problem for multinorm one tori, II
Sumito Hasegawa, Kazuki Kanai, Yasuhiro Oki
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…
math.NT2025
The Hasse norm principle for some extensions of degree having square-free prime factors
Yasuhiro Oki
We determine the structure of the obstruction group of the Hasse norm principle for a finite separable extension of a global field of degree , where has a square-free…
math.AG2025
The rationality problem for multinorm one tori
Sumito Hasegawa, Kazuki Kanai, Yasuhiro Oki
In this paper, we study the rationality problem for multinorm one tori, a natural generalization of norm one tori. For multinorm one tori that split over finite Galois extensions w…