Uniformity of Space: Definition & Examples

  • Thread starter Thread starter alexfloo
  • Start date Start date
  • Tags Tags
    Space Uniformity
Click For Summary
The discussion centers on defining a concept of uniformity in spaces, specifically regarding the equivalence of two properties involving homeomorphisms between neighborhoods of points. It explores whether spaces where all points are indistinguishable in terms of their neighborhoods can be classified under a specific term. The conversation highlights the distinction between continuous bijections and homeomorphisms, noting that a continuous bijection does not guarantee homeomorphism without a continuous inverse. The participants clarify misconceptions about the definitions and properties of open sets in this context. Ultimately, the thread seeks to establish a clearer understanding of uniformity in topological spaces.
alexfloo
Messages
192
Reaction score
0
"Uniformity" of space

I have a question about terminology. Suppose we have a space X with the property that:

for all x, x' in X and neighborhood N of x, N is homeomorphic to some neighborhood N' of x'
OR
for all x, x' there exists a homeomorphism f:X→X s.t. f(x)=x'.

(I believe these are equivalent, but I haven't worked it out.) In some sense, these spaces are uniform (although I know that uniform space has its own meaning). There are no "distinguished" points, or different "types" of points. (Any open, simply-connected subset of Euclidean space has this property. Any closed subset of Euclidean space not equal to its boundary lacks it, since boundary points cannot be continuously mapped onto interior points.)

Is there a name for this?

EDIT: fixed an error.
 
Last edited:
Physics news on Phys.org


actually those 2 sentences are not equivalent since the continuous bijection doesn't guarantee the homeomorpic between neighborhood of x and x' , it must have continuous inverse to be homeomorphic
 


EDIT: You are correct. I'll add that in.
 


alexfloo said:
Continuous bijection should be sufficient:

Continuous X→Y means for each open OY subset of Y, f-1(OY)=OX is open in X. Bijection means that

f(OX)=f(f-1(OY))=OY,

so f-1 is also continuous.

Now you assume that all open sets are of the form f^{-1}(O_Y). This is not necessarily true.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 20 ·
Replies
20
Views
4K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 20 ·
Replies
20
Views
5K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
42
Views
10K