User Włodzimierz Holsztyński

21 votes

If all balls at $x$ and $y$ are isometric is there an isometry sending $x$ to $y$?

answered Oct 6, 2014 at 22:03

14 votes

Accepted

A question in general topology

answered Jan 3, 2015 at 8:54

13 votes

Can you write $\mathbb R^2$ as a disjoint union of two totally disconnected sets?

answered Feb 26, 2015 at 3:24

13 votes

One tetrahedron inside another tetrahedron

answered Feb 17, 2013 at 6:39

13 votes

How do the compact Hausdorff topologies sit in the lattice of all topologies on a set?

answered Jun 27, 2013 at 8:24

12 votes

Intrinsic definition of arc length

answered May 18, 2015 at 8:03

11 votes

Accepted

Topological spaces $(X,\tau)$ where $|\text{Cont}(X,X)| = |X|$

answered Feb 12, 2015 at 20:40

11 votes

Mathematical software wish list

answered Aug 8, 2015 at 8:06

11 votes

Accepted

Possible error in Nicolas Bourbaki's General Topology -I, Chapter 1 Exercise 2?

answered May 23, 2013 at 23:01

10 votes

Mathematical software wish list

answered Aug 8, 2015 at 8:17

10 votes

Accepted

Continuous functions with convex level sets

answered Jan 17, 2015 at 21:06

10 votes

A generalized diagonal?

answered Dec 28, 2014 at 21:31

9 votes

Does homeomorphic and isomorphic always imply homeomorphically isomorphic?

answered Feb 21, 2013 at 4:38

8 votes

Accepted

Common sizes of intersections

answered Jan 13, 2015 at 11:49

8 votes

Hausdorff spaces with trivial automorphism group

answered Dec 3, 2014 at 17:54

8 votes

What polygons can be shrunk into themselves?

answered Oct 7, 2014 at 10:20

8 votes

Accepted

Quotient of metric spaces

answered Feb 6, 2015 at 2:30

8 votes

Abstract connectedness

answered Mar 6, 2015 at 8:36

7 votes

Collection of conjectures and open problems in graph theory

answered Dec 26, 2014 at 7:49

7 votes

Nontrivial theorems with trivial proofs

answered Jul 24, 2013 at 18:18

7 votes

Is it true that $X\times I\sim Y\times I\implies X\sim Y$?

answered Jan 31, 2017 at 6:31

6 votes

Great mathematicians born 1850-1920 (ET Bell's book ≲ x ≲ Fields Medalists)

answered Feb 21, 2013 at 3:46

5 votes

Every continuous function is homotopic to a locally Lipschitz one

answered Apr 6, 2013 at 3:52

5 votes

Characterizing Convex Configurations of Quadrupels of Coplanar Points via Linear (In-)equalities between Distance Sums or Differences

answered Feb 17, 2013 at 5:04

5 votes

Which topological spaces are (topological) groups?

answered Feb 24, 2013 at 7:46

5 votes

Proofs that require fundamentally new ways of thinking

answered Jul 3, 2013 at 5:14

5 votes

Can anyone give me a good example of two interestingly different ordinary cohomology theories?

answered Jul 3, 2013 at 6:20

5 votes

Accepted

Perimeter of a 'trapped' convex set

answered Apr 14, 2014 at 8:01

5 votes

Examples of $G_\delta$ sets

answered Oct 31, 2014 at 5:13

5 votes

Collaboration or acknowledgment?

answered Jan 3, 2015 at 1:11

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171 Answers

If all balls at $x$ and $y$ are isometric is there an isometry sending $x$ to $y$?

A question in general topology

Can you write $\mathbb R^2$ as a disjoint union of two totally disconnected sets?

One tetrahedron inside another tetrahedron

How do the compact Hausdorff topologies sit in the lattice of all topologies on a set?

Intrinsic definition of arc length

Topological spaces $(X,\tau)$ where $|\text{Cont}(X,X)| = |X|$

Mathematical software wish list

Possible error in Nicolas Bourbaki's General Topology -I, Chapter 1 Exercise 2?

Mathematical software wish list

Continuous functions with convex level sets

A generalized diagonal?

Does homeomorphic and isomorphic always imply homeomorphically isomorphic?

Common sizes of intersections

Hausdorff spaces with trivial automorphism group

What polygons can be shrunk into themselves?

Quotient of metric spaces

Abstract connectedness

Collection of conjectures and open problems in graph theory

Nontrivial theorems with trivial proofs

Is it true that $X\times I\sim Y\times I\implies X\sim Y$?

Great mathematicians born 1850-1920 (ET Bell's book ≲ x ≲ Fields Medalists)

Every continuous function is homotopic to a locally Lipschitz one

Characterizing Convex Configurations of Quadrupels of Coplanar Points via Linear (In-)equalities between Distance Sums or Differences

Which topological spaces are (topological) groups?

Proofs that require fundamentally new ways of thinking

Can anyone give me a good example of two interestingly different ordinary cohomology theories?

Perimeter of a 'trapped' convex set

Examples of $G_\delta$ sets

Collaboration or acknowledgment?