Timeline for Is there a number field $K$ such that $K^\times / \mathbb{Q}^\times$ is finitely generated? [duplicate]
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Oct 2, 2022 at 8:31 | comment | added | YCor | Maybe there are refinements of this result. E.g., one could ask whether this group always has infinite $\mathbf{Q}$-rank (this time, when $K\neq L$ and $L$ is not algebraic over a finite field). This might follow from the given argument but I'm not competent enough to see this clearly. | |
Oct 2, 2022 at 8:28 | comment | added | YCor | As follows from this answer, for a field extension $K\subset L$, the group $L^*/K^*$ is finitely generated iff $K=L$ or $L$ is finite (i.e., never except in trivial cases). | |
Oct 2, 2022 at 7:47 | history | closed |
GH from MO abx Derek Holt gr.group-theory Users with the gr.group-theory badge or a synonym can single-handedly close gr.group-theory questions as duplicates and reopen them as needed. |
Duplicate of If L is a field extension of K, how big is L*/K*? | |
Oct 2, 2022 at 6:51 | review | Close votes | |||
Oct 2, 2022 at 7:51 | |||||
Oct 2, 2022 at 6:05 | comment | added | user127776 | You can assume the extension is Galois. Assuming that the degree of the extension is $n>1$. You still need to use the norm map. You also need to show that infinite number of primes appear as a factor in the image of the norm map that its exponent is not divisible by $n$. For this you just need to show infinite number of primes do not split in $\mathcal{O}_K$. | |
Oct 2, 2022 at 4:18 | history | asked | Bma | CC BY-SA 4.0 |