Timeline for About normal closure of cyclic subgroup
Current License: CC BY-SA 3.0
2 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 28, 2012 at 10:02 | comment | added | YCor | you can say more: if $\langle a\rangle^G$ is torsion-free, it is equal to $\langle a\rangle$. Indeed, since it is normal and isomorphic to $\mathbf{Z}$, all its finite index subgroups remain normal (because all subgroups of $\mathbf{Z}$ are characteristic in $\mathbf{Z}$). | |
| May 27, 2012 at 16:51 | history | answered | Autumn Kent | CC BY-SA 3.0 |