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Anton Petrunin
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Universal group?

I can construct a finitely presented group $G$ with the following property (which I use to construct something else).

Given a finitely preseted group $\Gamma$, there is a subgroup $G'\le G$ of finite index such that $$\Gamma=G'/\langle\mathrm{Tor}\\, G'\rangle ,$$ where $\mathrm{Tor}\\, G'\subset G'$ is the set of all elements of finite order.

I think to call such group $G$ universal.

Questions:

  • Was it already constructed?
  • Does it already has a name? Is there any closely related terminology?

P.S.

  • The group which I construct is in fact hyperbolic.
  • My construction is simple, but it takes 2--3 pages. Let me know if you see a short way to do it.
Anton Petrunin
  • 45k
  • 14
  • 135
  • 299