Topological property of the Cantor set

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Discussion Overview

The discussion revolves around the topological properties of the Cantor set, specifically regarding the homeomorphism of separable zero-dimensional metric spaces to subsets of the Cantor set. Participants explore the proof of this concept and related theorems.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Hedi proposes that any separable zero-dimensional metric space is homeomorphic to a subset of the Cantor set and seeks a proof for this assertion.
  • A participant suggests proving a theorem related to the embedding of spaces using functions that separate points from closed sets, hinting at the construction of functions based on a countable basis of clopen sets.
  • Another participant questions the injectivity of the resulting function from the space X into the product space, indicating a potential oversight.
  • A later reply proposes that the injectivity may be assured due to the Hausdorff property of the space X, seeking confirmation of this idea.

Areas of Agreement / Disagreement

Participants express differing views on the injectivity of the function derived from the embedding, with some uncertainty regarding the implications of the Hausdorff property. The discussion remains unresolved regarding the proof and the injectivity issue.

Contextual Notes

Participants have not fully established the implications of the Hausdorff condition on injectivity, and the proof of the initial claim about homeomorphism remains incomplete.

hedipaldi
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Let X be a metric separable metric and zero dimensional space.Then X is homeomorphic to a subset of Cantor set.
How can it be proved?
Thank's a lot,
Hedi
 
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Hint: prove the following theorem:

  • Let ##X## be a ##T_1## space (= singletons are closed). Let ##\{f_i~\vert~i\in I\}## be a collection of functions ##f_i:X\rightarrow X_i## which separates points from closed sets, then the evaluation map ##e:X\rightarrow \prod_{i\in I}X_i## is an embedding.

Now, your space ##X## has a countable basis consisting of clopen sets (why?). Use this to construct functions ##f_n:X\rightarrow \{0,1\}## for ##n\in \mathbb{N}## and apply the theorem.
 
Thank you.
 
Injectivity of the function

The resulting function from X into the product space doesn't seem to be one-to-one.Maybe i fail to see something?
 
After further thinking i suppose injectivity is due to X being Haussdorff.Am i right?
 

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