Skip to main content
10 events
when toggle format what by license comment
Feb 12, 2021 at 1:21 history edited Sebastien Palcoux CC BY-SA 4.0
forgot unital
Jun 15, 2016 at 16:59 comment added Sebastien Palcoux @MarcelBischoff: No, see the answer here: mathoverflow.net/q/242271/34538
Jun 13, 2016 at 19:14 comment added Marcel Bischoff Ok, I see, I was already expecting that this is automatic. Is $G$ necessarily abelian?
Jun 13, 2016 at 19:11 comment added Sebastien Palcoux @MarcelBischoff: It is a Gelfand pair in this case because $\forall h_1, h_2, h_3 \in H \subset G\rtimes H$ and $\forall g,g' \in G \subset G\rtimes H$, we have: $$ h_1gh_2g'h_3 = h_1 g \sigma_{h_2}(g') h_2 h_3 = h_1 \sigma_{h_2}(g') g h_2 h_3 = h_1 h_2 g' h_2^{-1} g h_2h_3 $$ which means that $HgHg'H = Hg'HgH$, i.e. the double coset algebra is commutative.
Jun 13, 2016 at 18:19 history edited Sebastien Palcoux CC BY-SA 3.0
No, no, no..., A_4 is not abelian!!!
Jun 13, 2016 at 18:04 comment added Marcel Bischoff It is necessary, that the double coset algebra $H\backslash (G\rtimes H) /H$ is commutative, i.e. $(G\rtimes H,H)$ has to be a Gelfand pair. Namely, one two box space is $\mathbb{C}^N$ where $N$ is the number of double cosets, while the other is the double coset algebra itself.
Jun 13, 2016 at 18:03 history edited Sebastien Palcoux CC BY-SA 3.0
This form is not sufficient. Is it necessary.
Jun 11, 2016 at 15:47 history edited Sebastien Palcoux CC BY-SA 3.0
edited body
Jun 11, 2016 at 15:40 history edited Sebastien Palcoux CC BY-SA 3.0
added 135 characters in body
Jun 11, 2016 at 15:34 history asked Sebastien Palcoux CC BY-SA 3.0