Timeline for Subgroups of $SL_2(\mathbb R)$ which contain $SL_2(\mathbb Z)$ as a finite index subgroup
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 22, 2016 at 2:15 | history | edited | Venkataramana | CC BY-SA 3.0 |
$I had written $\lambda-1$ ; this should read $\lambda =-1$
|
| Oct 13, 2016 at 10:03 | vote | accept | Honing | ||
| Oct 13, 2016 at 9:02 | comment | added | Venkataramana | @Honig: not quite. If $G$ is a Chevalley group which is simply connected, then yes. Otherwise, there are conditions. There are results by Adler about these matters (there is an article in the Algebraic Groups and Discontinuous subgroups edited by Borel, where these issues are discussed). | |
| Oct 13, 2016 at 8:13 | comment | added | Honing | @Venkataramana Thank you for your answer. Is it a general fact of life that, if $G$ is a connected reductive group over $\mathbb Z$, then $G(\mathbb Z)$ is a maximal arithmetic subgroup of $G(\mathbb Q)$? | |
| Oct 13, 2016 at 7:49 | history | edited | Uri Bader | CC BY-SA 3.0 |
edited body
|
| Oct 13, 2016 at 7:02 | history | edited | Friedrich Knop | CC BY-SA 3.0 |
deleted 1 character in body
|
| Oct 13, 2016 at 6:45 | history | edited | Venkataramana | CC BY-SA 3.0 |
added 56 characters in body
|
| Oct 13, 2016 at 6:36 | history | edited | Venkataramana | CC BY-SA 3.0 |
added 114 characters in body
|
| Oct 13, 2016 at 6:34 | comment | added | Venkataramana | Oops, you are right. I meant to write every intermediate subgroup contains the integral subgroup of infinite index | |
| Oct 13, 2016 at 6:30 | comment | added | Venkataramana | That is not the claim: every intermediate subgroup contains the integral symp group as an infinite index subgroup. Pls read carefully | |
| Oct 13, 2016 at 4:56 | comment | added | YCor | $Sp_{2g}(\mathbf{Z})$ is not maximal in $Sp_{2g}(\mathbf{Q})$ (an intermediate subgroup is $Sp_{2g}(\mathbf{Z}[1/2])$). Actually, a finitely generated group cannot be maximal in an infinitely generated group since any group is generated by any of its maximal subgroups and one further element. | |
| Oct 13, 2016 at 3:30 | history | edited | Venkataramana | CC BY-SA 3.0 |
fixed notation
|
| Oct 13, 2016 at 2:00 | history | edited | Venkataramana | CC BY-SA 3.0 |
added 27 characters in body
|
| Oct 13, 2016 at 1:41 | history | answered | Venkataramana | CC BY-SA 3.0 |