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2 votes
1 answer
203 views

Commensurability classes of subgroups of a nilpotent group

Here is a question I stumbled upon in my research. Question: Given a finitely generated nilpotent group $G$, do its subgroups fall into finitely many abstract commensurability classes? Recall that two ...
Corentin B's user avatar
  • 1,819
5 votes
1 answer
200 views

Example of an invariant metric on a nilpotent group which is not asymptotically geodesic

Let $X$ be a metric space. We say that $X$ is asymptotically geodesic if for all $\epsilon > 0$, there exists $R > 0$ such that, for all $x,y \in X$, there exists some finite sequence of points $...
Christian Gorski's user avatar
5 votes
0 answers
183 views

Finitely generated nilpotent groups as cusp groups

I recently learned about the following question, asked by I. Kapovich : Is there an example of a group $G$ which is hyperbolic relative to some parabolic subgroups that are nilpotent of class $\geq 3$...
M. Dus's user avatar
  • 2,090
1 vote
1 answer
101 views

Relation between flat and nilpotent structures on fibers?

When collapsing Riemannian manifolds under suitable curvature conditions, two types of structure arise on the fibers: flat structures and nilpotent structures. This depends on the scale at which one ...
Mikhail Katz's user avatar
  • 16.6k
11 votes
2 answers
755 views

Quasi-isometric rigidity of Nil

Let $Nil$ be the unique simply connected non-abelian three-dimensional nilpotent Lie group, i.e. the group of upper triangular matrices with all the eigenvalues equal to 1 (this group is also known as ...
Roberto Frigerio's user avatar
2 votes
1 answer
846 views

Word metrics and finite index subgroups

Suppose that we are given some finitely generated group $ G $ and some finite index subgroup of it $ H $. Given a finite generating symmetric generating set $ S \subset G $, we can define the word ...
Miel Sharf's user avatar
5 votes
0 answers
126 views

Regularity of polynomial growth of groups

Let $G$ be a finitely generated group of polynomial growth. This means that the size $B_n$ of the ball of radius $n$ satsifies: $$ A n^d \leq B_n \leq Bn^d $$ for some constants $A$, $B$. My question ...
Michal Kotowski's user avatar
4 votes
1 answer
855 views

On Canonical generators of torsion free nilpotent group

I read somewhere that Maltcev proved that for any finitely generated torsion free Nilpotent group $G$ there are canonical generators, i.e. $g_{1},\ldots,g_{k}$ such that any $g \in G$ can be written ...
Jonathan Hermon's user avatar