312 reputation
18
bio website rupertmccallum.com
location Germany
age 38
visits member for 3 years, 3 months
seen Sep 11 at 8:11
I am doing a post-doctoral research position about topological buildings and topological groups at the University of M√ľnster.

Aug
26
awarded  Popular Question
Jul
2
awarded  Curious
May
26
comment when the derived group of the group of $k$-rational points has nonempty interior in the strong topology
Many thanks for your help. Peter McNamara, can I ask you to elaborate further about the anisotropic case. I was told that the only examples of anisotropic absolutely quasi-simple algebraic groups over local fields of positive characteristic were of the form $\mathrm{SL}_{1}(\Delta)$ for central simple division algebras $\Delta$, and that the derived group $[G(k),G(k)]$ was equal to the group of norm-1 units in the unique maximal order of $\Delta$, which I thought was open in the strong topology? Does this include your anisotropic form of $\mathrm{PGL_p}$?
May
26
accepted when the derived group of the group of $k$-rational points has nonempty interior in the strong topology
May
19
comment when the derived group of the group of $k$-rational points has nonempty interior in the strong topology
Many thanks for your help. Yes, strong topology does mean the topology coming from the topology on $k$. I think I heard that phrase used somewhere in an algebraic geometry textbook but I'm not sure. Do you know of anywhere where I can read more about the Steinberg presentation?
May
15
asked when the derived group of the group of $k$-rational points has nonempty interior in the strong topology
May
8
accepted an algebraic group where the function field is not separable over the ground field
May
7
asked an algebraic group where the function field is not separable over the ground field
May
7
accepted A strengthened version of Noether's normalisation lemma?
May
6
asked A strengthened version of Noether's normalisation lemma?
Apr
24
comment ubiquity of free subgroups of special linear groups
Many thanks for all the comments. Gregory Soifer has advised me about a paper he wrote earlier with his student S. Vishkautsan, which would seem to cover the special case of what I am saying when the ground field is $\mathbb{R}$. It looks as though what I am saying is not really all that new.
Apr
24
accepted ubiquity of free subgroups of special linear groups
Apr
15
awarded  Commentator
Apr
15
comment Is the group of rational points of an anisotropic absolutely quasi-simple algebraic group over a non-archimedean local field known to be perfect?
Many thanks, I wonder if you could give me a reference for a proof of the fact that those are the only examples, is it in Platonov's book?
Apr
14
asked Is the group of rational points of an anisotropic absolutely quasi-simple algebraic group over a non-archimedean local field known to be perfect?
Apr
14
asked abstract simplicity results for anisotropic quasi-simple algebraic groups defined over a non-archimedean local field
Mar
29
accepted How do you prove that Q+Con(PA) can't be interpreted in ACA_0?
Mar
27
awarded  Editor
Mar
27
revised How do you prove that Q+Con(PA) can't be interpreted in ACA_0?
added 405 characters in body
Mar
27
asked How do you prove that Q+Con(PA) can't be interpreted in ACA_0?