Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 6514

Continuum theory, point-set topology, spaces with algebraic structure, foundations, dimension theory, local and global properties.

25 votes
Accepted

A question about connected subsets of $[0,1]^2$

A counterexample to this statement was posted as a comment by Dejan Govc to the Math StackExchange question, Do partitions of a square into two sets always connect one pair of opposite edges?. For $0 …
Jim Belk's user avatar
  • 8,483
26 votes

Can non-homeomorphic spaces have homeomorphic squares?

Yes. Let $M$ be the Whitehead Manifold, which has the property that $M \not\cong \mathbb{R}^3$, but $M\times\mathbb{R}^3 \cong \mathbb{R}^6$. (In fact $M\times\mathbb{R} \cong \mathbb{R}^4$.) Let $$ …
Jim Belk's user avatar
  • 8,483
7 votes
Accepted

Extending a map from $S^n\to M^n$ to a nice map from $B^{n+1}\to M^n$

The answer is no, essentially since higher homotopy groups of spheres are nontrivial. For example, in the $n=3$ case let $M=B^3$ and let $\sigma\colon S^3 \to M$ be the Hopf map from $S^3$ to the bou …
Jim Belk's user avatar
  • 8,483