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5 votes
0 answers
296 views

For which classes of metric spaces can we prove that quasi-isometry is an equivalence relation in ZF?

Given two metric spaces $(M_1, d_1)$ and $(M_2, d_2)$, a map $\phi \colon (M_1, d_1) \to (M_2, d_2)$ is a large-scale Lipschitz essentially surjective map if there exist constants $A \geq 1, B \geq 0$,...
Carl-Fredrik Nyberg Brodda's user avatar
4 votes
0 answers
114 views

Sufficient conditions for the Besicovitch covering theorem to hold on groups of polynomial growth

Let $G$ be a finitely generated group with symmetric generating set $S$. Then $S$ induces a distance $d$ on $G$ by letting $d(a,b) = $ the minimum $n$ such that there are generators $s_1,...,s_n$ with ...
MathidRyan's user avatar
2 votes
0 answers
115 views

Definition of the category QMet of metric spaces and quasi-isometries

I am following Clara Löh's Geometric Group Theory. An Introduction, and in remark 5.1.12, she defines the category QMet whose objects are metric spaces and whose morphisms are quasi-isometric ...
Saúl RM's user avatar
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1 vote
1 answer
162 views

Divergence functions in hyperbolic groups

Gromov hyperbolicity has many characterizations, one of them being the existence of a super-linear divergence function, see definition below. We note that in $\mathbb{R}^2$ there is no divergence ...
Strichcoder's user avatar
1 vote
1 answer
221 views

What properties are preserved by quasi-isometries

Recently, I came across the notion of quasi-isometries, while thinking of "discrete spaces which are surrogates for approximate continuous ones". What (metric)/geometric properties are ...
ABIM's user avatar
  • 5,405
1 vote
0 answers
238 views

Example of CAT($k$) space [closed]

Good time of day. I repeat the question from MSE (https://math.stackexchange.com/questions/4464888/question-about-example-of-catk-space) because no response has been received.Question is the following:...
UserIn's user avatar
  • 103