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Jan
7 |
comment |
When can a locally compact group be approximated by discrete subgroups?
I don't know if this helps for the application you have in mind, but for t.d.l.c. groups, an alternative way to approximate the group by discrete objects is to look instead at coset spaces $G/U$ where $U$ ranges over a base of identity neighbourhoods consisting of compact open subgroups. If $G$ is a SIN group, then you can also make $U$ normal in $G$, so $G/U$ is a discrete quotient group of $G$ in the natural sense. |
Jan
1 |
reviewed | Approve The injection of direct image sheaf |
Dec
10 |
reviewed | Approve Projective closure of affine curve |
Dec
10 |
reviewed | Approve Number of spanning trees which contain a given edge |
Dec
10 |
revised |
Distal actions on coset spaces
added 439 characters in body |
Dec
10 |
revised |
Can Calabi-Yau manifolds have nonabelian discrete symmetry groups?
edited tags |
Dec
7 |
revised |
Distal actions on coset spaces
added 175 characters in body |
Dec
7 |
asked | Distal actions on coset spaces |
Dec
6 |
reviewed | Approve Completion of modules of differentials (A strange exercise in Liu's AG textbook) |
Dec
5 |
reviewed | Approve Mystery behind ADE Dynkin diagram |
Dec
3 |
answered | Wild automorphisms of profinite groups |
Nov
10 |
comment |
What are some very important papers published in non-top journals?
@GerryMyerson: Indeed, thanks! |
Nov
8 |
comment |
What are some very important papers published in non-top journals?
I think there was a similar question (which I can't find right now) about important original theorems appearing in books rather than journals. The Dicks-Dunwoody almost stability theorem comes to mind (although it is slightly before the cutoff date). |
Oct
27 |
comment |
A generalization of residual finiteness to topological groups
A discrete cocompact normal subgroup $\Lambda$ is already a lot to ask for. For instance, if your group is compactly generated, then any such $\Lambda$ must have open centraliser, so if $G$ is connected then $\Lambda$ would be central, and if $G$ is totally disconnected you'd have a finite index subgroup of the form $\Lambda \times U$ where $U$ is a compact open subgroup. |
Oct
22 |
revised |
Not especially famous, long-open problems which anyone can understand
added 207 characters in body |
Oct
22 |
answered | Not especially famous, long-open problems which anyone can understand |
Sep
23 |
revised |
Just-not-nilpotent-by-compact quotient of a locally compact group
added 73 characters in body |
Sep
23 |
answered | Just-not-nilpotent-by-compact quotient of a locally compact group |
Sep
16 |
comment |
Actions on spaces with measured walls
Groups acting on $\mathbb{R}$-trees could be a good special case to consider. |
Sep
14 |
awarded | Civic Duty |