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10h
revised Compact Sets Metric Spaces
edited tags
10h
answered Compact Sets Metric Spaces
2d
awarded  Guru
Jan
28
comment When are two direct products of groups isomorphic?
I thought the argument was due to Vipul Naik: math.stackexchange.com/a/427640/36434.
Jan
28
answered When are two direct products of groups isomorphic?
Jan
27
answered Normalizer of an element of a free group
Jan
27
comment Normalizer of an element of a free group
Normalizer or centralizer? In fact, I do not know the definition of the normalizer of an element, but just of a subset.
Jan
24
comment A question about group actions on a trees
As stated, the statement seems to be false: let $\mathbb{Z}^2$ act on the line $\mathbb{R}$ by $(m,n) \cdot x \mapsto x+m+n$, and consider $H= \langle (1,0) \rangle$, $g=(0,1)$. Then $\Gamma_H= \mathbb{R}= \mathrm{Axis}(g)$.
Jan
24
accepted Gromov-Hausdorff convergence to a circle
Jan
19
comment How can I work out if a certain group presentation implies a certain relation?
@JackM: I do not really understand your question, but the group you consider is just the right-angled Artin group associated to a cycle of length $k$.
Jan
19
answered If consecutive elements commute each other, does it mean that all of them commutes with each other?
Jan
17
answered First Order Logic and groups: Prove that no $T$ exists such that $M \vDash T \cup T_{grp}$ **IFF**
Jan
8
comment Cone over a circle.
What do you mean by characteristic here? Did you want to say curvature?
Jan
8
awarded  Popular Question
Jan
6
revised Simplicial complex and link
added 46 characters in body; edited tags
Jan
6
revised Shapes of a simplicial complex
added 24 characters in body; edited tags
Jan
6
answered Shapes of a simplicial complex
Dec
30
comment Shift and ergodic measures
Indeed, the proof is pretty elementary. You do not need to fill in all the details, but an expanded answer would be pleasant.
Dec
23
comment Proper action and compactness
I am not sure to understand your problem: compactness of the balls is not needed, they just apply their definition of properness.
Dec
22
comment Proper action and compactness
The authors use a different definition of properness, see I.8.3(1).