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 124004

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

6 votes
Accepted

Is the dimension given by Klee trick ever sharp?

Are the embeddings required to be isometric embeddings? If not, then what about including three points into $\mathbb{R}$ in two ways, so that the middle point of the three changes? More explicitly, …
IJL's user avatar
  • 3,451
6 votes

Cover the $n$-disc irredundantly with $n+1$ open sets. Suppose that the $(n+1)$-fold interse...

It is not true in general. Let $n=3$, and take a piece of a brick wall (thickness one brick) that is homeomorphic to a 3-disc. For example, just take a largish rectangular wall. There are bricks of …
IJL's user avatar
  • 3,451
12 votes
Accepted

Quotient of solid torus by swapping coordinates on boundary

Your quotient manifold is homeomorphic to $S^3$. I know this because it is a closed 3-manifold and its fundamental group is trivial, so I'm quoting the Poincare conjecture/Perelmann's theorem. The f …
IJL's user avatar
  • 3,451
0 votes

How can I construct a closed manifold from a finite CW complex?

The mod-2 homology groups of any closed $n$-manifold are `$n$-palindromic' by Poincare duality, i.e., $H_m(M;\mathbb{Z}/2)\cong H_{n-m}(M;\mathbb{Z}/2)$ for each $m$. If the mod-2 homology of $X$ is …
IJL's user avatar
  • 3,451