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Feb
2
awarded  Enlightened
Feb
2
awarded  Nice Answer
Jan
30
comment What dihedral subgroups occur in the affine general linear group $AGL(2,3)$
G := AutomorphismGroup(SylowSubgroup(GL(3,3),3));; L := List(ConjugacyClassesSubgroups(G), StructureDesription(Representative)));
Jan
30
comment What dihedral subgroups occur in the affine general linear group $AGL(2,3)$
According to GAP, you can also find the dihedral group of order $12$.
Jan
30
comment Is $SL_n(\mathbb{R})$ actually simple?
See eg "Classical Groups and Geometric Algebra" by Grove. This result is proved in the beginning of the book.
Jan
28
answered Group conjecture
Jan
16
answered When is every group of order $n$ nilpotent of class $\leq c$?
Dec
10
answered How many groups of order $n$ with center {e} exist?
Nov
13
awarded  Popular Question
Nov
11
awarded  Nice Question
Oct
10
awarded  Yearling
Oct
7
comment Centralizer $C_G(T)$ of a maximal torus $T$ is in every Borel subgroup containing $T$?
That's just $xC_G(T)x^{-1} = C_G(xTx^{-1})$, true in any group $G$ for any subgroup $T$.
Oct
7
comment Centralizer $C_G(T)$ of a maximal torus $T$ is in every Borel subgroup containing $T$?
What you want is $gbg^{-1} (gTg^{-1}) (gbg^{-1})^{-1} = T$, so $gbTb^{-1}g^{-1} = T$. Then $gb$ normalizes $C_G(T)$ and $C_G(T) < B$, so $C_G(T) < gBg^{-1}$
Oct
7
answered Centralizer $C_G(T)$ of a maximal torus $T$ is in every Borel subgroup containing $T$?
Oct
6
answered Why is a parabolic subgroup $P$ connected?
Sep
29
comment Special case of Schur-Zassenhaus theorem
@DerekHolt: I agree. But it avoids group cohomology which was asked for..
Sep
29
answered Special case of Schur-Zassenhaus theorem
Sep
23
answered Is it possible to write every even permutation in $S_n$ as a square of some even permutation?
Sep
21
revised $G' = [A, B]$ if $G = AB$, where $A,B$ are abelian.
added 17 characters in body
Sep
21
comment $G' = [A, B]$ if $G = AB$, where $A,B$ are abelian.
@J.G.: Ok, done