Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

We study the structure of the Mordell–Weil groups of semiabelian varieties over large algebraic extensions of a finitely generated field of characteristic zero. We consider two types of algebraic extensions in this paper; one is of extensions obtained by adjoining the coordinates of certain points of various semiabelian varieties; the other is of extensions obtained as the fixed subfield in an algebraically closed field by a finite number of automorphisms. Some of such fields turn out to be new examples of Kummer-faithful fields which are not sub-p-adic. Among them, we find both examples of Kummer-faithful fields over which the Mordell–Weil group modulo torsion can be free of infinite rank and not free.

DOI： 10.1007/s40993-025-00658-2

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Other Link： https://link.springer.com/article/10.1007/s40993-025-00658-2/fulltext.html

Language：Japanese   Publishing type：Research paper (scientific journal)  

This study aims to gather insights into the design and implementation of a Preparing Future Faculty (PFF) Program for graduate students at science and engineering universities. A survey was conducted on faculty and staff at 20 national and private universities in Japan about the scope of participants, formats of implementation, contents of the program, and evaluation methods of the PFF program. The results revealed that at major national universities, PFF programs are offered as standard graduate education (official) courses and implemented throughout campuses together with university teaching assistant training. The structure of the PFF program focuses on content related to course design, which is essential for teaching practices. Based on the results, the study discusses the selection of program contents and conduct of teaching practicum for highly skilled teaching assistants who are capable of partially handling introductory science courses within the framework of PFF training. The study also identified challenges involved in the continuous operation of PFF programs. In particular, the program needs to raise awareness in universities, secure a steady number of participants, and ensure the availability of staff to administer the PFF.

DOI： 10.14943/J.HighEdu.32.47

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Mathematical Institute, Tohoku University  

In this paper, we study the ramification of extensions of a function field generated by division points of rank 2 Drinfeld modules. Also conductors of certain rank 2 Drinfeld modules are defined as analogues of those for elliptic curves. A calculation of these conductors allows us to show an analogue of Szpiro's conjecture under a certain limited situation.

DOI： 10.2748/tmj.20230224

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

Geyer and Jarden proved several results for torsion points of elliptic curves defined over the fixed field by finitely many elements in the absolute Galois group of a finitely generated field over the prime field in its algebraic closure. As an analogue of these results, this paper studies torsion points of Drinfeld modules defined over the fixed field by finitely many elements in the absolute Galois group of a finitely generated function field in its algebraic closure. We prove some results which are similar to those of Geyer and Jarden.

DOI： 10.1016/j.jnt.2021.03.014

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Event date： 2026.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：University of Yamanashi  

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Event date： 2025.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Kanagawa University  

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Event date： 2025.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Research Institute for Mathematical Sciences, Kyoto University  

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Event date： 2024.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Iwate Prefectural University  

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Event date： 2024.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Tohoku University  

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