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seen Jun 20 at 9:39

May
16
accepted Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
May
7
awarded  Good Answer
Apr
28
comment Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
Thanks for the reposting and the clarification regarding SO(Q).
Apr
27
comment Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
Dear few_reps: I have read your answer and am trying to see if I can make your proof and the one given below by Paul work for SO(Q). Please repost your answer. I will give feedback soon.
Apr
27
awarded  Popular Question
Apr
20
comment Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
Thank Paul, I fixed it.
Apr
20
revised Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
deleted 2 characters in body
Apr
20
asked Orbits of the maximal compact subgroup on the light cone for $p$-adic groups
Apr
2
asked A variant of Nelson-Hadwiger Problem on the chromatic number of the plane
Mar
31
accepted In what sense is the classification of all finite groups “impossible”?
Jan
29
awarded  Yearling
Oct
17
awarded  Popular Question
Oct
16
awarded  Nice Answer
Sep
11
awarded  Nice Question
Sep
8
comment In what sense is the classification of all finite groups “impossible”?
@StefanKohl: Well, I take CFSG as a complete classification, even though it does not answer all questions that one can pose about the finite simple groups. Such a listing would be perfectly OK. My question is, whether there are any obvious obstruction that one cannot expect to come up with such a list for all groups. For instance, the classification of the groups of order $p^n$ gets increasingly complicated with $n$, but so does the classification of $n \times n$ matrices up to conjugacy (Jordan form), so in what sense is the classification of groups of prime power "impossible"?
Sep
8
asked In what sense is the classification of all finite groups “impossible”?
Aug
24
awarded  Nice Answer
Aug
23
comment A question about “Zariski dense” arguments
Yes, but there is no "subtraction" possible in the space $Y$ above. Let me rephrase the argument: the set of matrices $A$ with $p_A(A)=0$ is closed, (because it is the pre-image of $0$ under the map $ A \mapsto p_A(A)$ that $\{ 0 \}$). Since it contains a dense set, it has to be the entire space. You do not need to use the diagonal.
Aug
23
answered A question about “Zariski dense” arguments
Aug
6
comment $p$-adic analogues of $SO(3)$
user52824: Thank you for the enlightening comment. I soon have to deal with several other cases (including different ${\mathbf Q}_p$-forms of ${\mathrm{SO}}_4$.) It would be great if you could please provide a reference that explains how to systematically find all these forms.