Tyrone's user avatar
Tyrone's user avatar
Tyrone's user avatar
Tyrone
  • Member for 9 years, 8 months
  • Last seen this week
  • Beijing, China
24 votes
Accepted

Is the Alexander horned sphere a cofibration?

18 votes
Accepted

Action of the degree 2 map on $\pi_8(S^4)$

17 votes
Accepted

Are all homotopy equivalences realized by fibrations over [0,1]?

11 votes
Accepted

Compact-open topology and Delta-generated spaces

11 votes
Accepted

Finite domination and compact ENRs

11 votes
Accepted

Vector bundle over an oriented manifold with non-vanishing w_2w_3

11 votes
Accepted

The fifth k-invariant of BSO(3)

11 votes
Accepted

Does the category of locally compact Hausdorff spaces with proper maps have products?

8 votes
Accepted

An integral cohomology operation related to Steenrod square?

8 votes
Accepted

Spaces that are contractible mod diagonal

8 votes
Accepted

Does $\pi_1(H)=0\Rightarrow \pi_3(G/H)=0$ for a simple and simply connected Lie group $G$?

7 votes

Countable chain condition in topology

7 votes
Accepted

Fundamental group of the space of maps into a classifying space

7 votes
Accepted

Retracting a wedge of spheres off a homotopy fiber

7 votes

(Co)homology theories not satisfying the wedge axiom

6 votes
Accepted

Are all monotonically normal manifolds of dimension at least two metrizable?

5 votes

Induced maps on homotopy groups by self maps of $\mathbb{CP}^n$

5 votes
Accepted

Is $\Omega J_{p^n-1}S^2$ commutative up to homotopy?

5 votes
Accepted

Ultrafilters of closed sets

4 votes
Accepted

Making CW-complexes metrizable

4 votes

The classifying space of any topological group is paracompact and locally contractible

4 votes
Accepted

Does the group of compactly supported diffeomorphisms have the homotopy type of a CW complex?

3 votes

Which closed subsets $Y$ of a compact space $X$ admit a linear extensor $C(Y)\to C(X)$?

3 votes

For which $X$ is $X\times I$ collectionwise normal?

3 votes
Accepted

Sets with a good lift under a covering

3 votes
Accepted

When is a contractible space a retract of the Hilbert cube or $\Bbb R^\omega$?

3 votes
Accepted

Is the fine uniformity generated by all continuous pseudometrics?

3 votes

Equivalent definition of a homotopy of functions

3 votes

Homotopy domination of a wedge of two polyhedra

3 votes

Computation of $\pi_4$ of simple Lie groups