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Dec 28, 2015 at 17:44 answer added Geoff Robinson timeline score: 1
Dec 14, 2015 at 16:23 comment added Ashot Minasyan An interesting example of a normal group is any free group. Indeed, a classical theorem of W. Magnus states that if two elements $r,s$, of a free group, have the same normal closures then $r$ is conjugate to $s^{\pm 1}$.
Dec 11, 2015 at 11:25 answer added Derek Holt timeline score: 5
Dec 11, 2015 at 1:26 answer added Will Sawin timeline score: 8
Dec 10, 2015 at 23:16 answer added YCor timeline score: 7
Dec 10, 2015 at 22:18 comment added YCor "What is the largest family of normal groups?" The answer is "the family of all normal groups" :)
Dec 10, 2015 at 22:17 comment added Farid Aliniaeifard @SamHopkins The reason I call such groups normal was it seams that they have a lot of normal subgroups.
Dec 10, 2015 at 21:57 comment added YCor With no symbols, the definition of "normal" is: whenever two cyclic subgroups generate the same normal subgroup, they are conjugate.
Dec 10, 2015 at 21:56 comment added Sam Hopkins "Normal" is surely a bad choice of terminology...
Dec 10, 2015 at 21:51 history edited Arturo Magidin CC BY-SA 3.0
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Dec 10, 2015 at 21:45 history edited Arturo Magidin CC BY-SA 3.0
edited title
Dec 10, 2015 at 21:09 comment added Fan Zheng @FaridAliniaeifard Sorry I didn't see you mean the subgroup generated by these elements.
Dec 10, 2015 at 20:53 history edited Farid Aliniaeifard CC BY-SA 3.0
added 9 characters in body
Dec 10, 2015 at 20:44 comment added Farid Aliniaeifard Not necessarily $r=xsx^{-1}$ since r could be a product of the elements of $\langle gsg^{-1}: g\in G \rangle $.
Dec 10, 2015 at 20:34 comment added Fan Zheng I'm afraid there is possibly some serious confusion here: $r=ere^{-1}\in <grg^{-1}:g\in G>=<gsg^{-1}:g\in G>$, so there is always some $x\in G$ such that $r=xsx^{-1}$.
Dec 10, 2015 at 20:28 history edited Arturo Magidin CC BY-SA 3.0
rephase, clarify.
Dec 10, 2015 at 18:59 history asked Farid Aliniaeifard CC BY-SA 3.0