HenrikRüping's user avatar
HenrikRüping's user avatar
HenrikRüping's user avatar
HenrikRüping
  • Member for 14 years, 1 month
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21 votes

Example of an unnatural isomorphism

19 votes

Proving that a group is free

17 votes

The free group $F_2$ has index 12 in SL(2,$\mathbb{Z}$)

16 votes

Are there space filling curves for the Hilbert cube?

13 votes

Examples of common false beliefs in mathematics

12 votes

Results in linear algebra that depend on the choice of field

11 votes
Accepted

Isomorphic morphisms. A 27-morphism category

11 votes
Accepted

Homeomorphism-fixing subsets

8 votes
Accepted

Which functors preserve the number of connected components?

8 votes

What is an explicit example of a sequence converging to two different points?

8 votes
Accepted

homotopy associative $H$-space and $coH$-space

8 votes
Accepted

A mutation of the Collatz disease

7 votes
Accepted

Criteria for extending vector field on sphere to ball

7 votes

Integrability of derivatives

7 votes

Applications of homotopy groups of spheres

7 votes
Accepted

Question about spectral sequences associated to filtered complexes with unbounded filtrations

7 votes

Visualizing hyperbolic metric of punctured sphere

7 votes

When is a extension of $\mathbb{Z}$ by a free group a CAT(0) group?

6 votes

Examples of non-metrizable spaces

6 votes
Accepted

The fundamental group of an $S^1$-quotient

6 votes
Accepted

Massey Products on a specific space

6 votes
Accepted

An example of a regular but not linear-based topological space

6 votes

When are two semidirect products of two cyclic groups isomorphic

6 votes

What is the intuitive difference between these two simplicial subdivision functors?

5 votes

Obstructions to $E_2$-algebra structure on $E_1$-algebra

5 votes

Adem relations of Steenrod square without modding out the coboundaries

5 votes
Accepted

Question about exotic spheres

5 votes

How to solve $f(f(x)) = \cos(x)$?

5 votes

Topological description of Manifold with boundary

4 votes

Pascal triangle and prime numbers