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Freeness of Mordell–Weil groups over finite extensions of K[σ] when e = 1

Determine whether, for a finitely generated field K over Q and e = 1, for almost all σ ∈ G_K, any finite extension L of K[σ] and any semiabelian variety A of positive dimension over L satisfy that A(L)/A(L)tor is a free abelian group of countably infinite rank.

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Background

Theorem 4.1 proves that for e ≥ 2, and almost all σ ∈ G_Ke, the Mordell–Weil group modulo torsion over finite extensions of K[σ] is free of countably infinite rank for all positive-dimensional semiabelian varieties. The case e = 1 is not accessible by the methods used, primarily because torsion in tori and abelian varieties can be infinite over K(σ) when e = 1.

References

It is not known whether Theorem 4.1 still holds in the case e = 1.

Mordell--Weil groups over large algebraic extensions of fields of characteristic zero (2408.03495 - Asayama et al., 7 Aug 2024) in Remark 4.4