How Does the Cantor Set Compare to the Cardinality of Real Numbers?

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Homework Help Overview

The discussion revolves around the comparison of the Cantor set's cardinality to that of the real numbers. The original poster seeks feedback on their proof regarding this relationship and is interested in extending their argument to demonstrate that the Cantor set has the same cardinality as the real numbers.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the original poster's proof and its technical correctness. There is mention of using ternary expansions to illustrate the cardinality of the Cantor set compared to the reals. Questions are raised about the visibility of attachments and the implications of using different file formats for sharing proofs.

Discussion Status

The discussion is ongoing, with some participants providing feedback on the proof and raising questions about the Cantor set's Lebesgue measure. There is no explicit consensus yet, but participants are engaging with the original poster's ideas and seeking clarification.

Contextual Notes

There are constraints related to the approval process for attachments, which may affect the sharing of the original poster's proof. Additionally, the discussion includes assumptions about the properties of the Cantor set and its measure, which are being questioned.

benorin
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So the problem, and my partial solution are in the attached PDF.

I would like feedback on my proof of the first statement, if it is technically correct and if it is good. Any ideas as to how I can use/generalize/extend the present proof to proof the second statement, namely that E (the Cantor set) has the same cardinality as [tex]\mathbb{R}[/tex]? Please, not the ternary expansion correspondence to the reals in [0,1]:biggrin: .
 

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You might consider summarizing your arguments here since your attachment isn't visible until it gets approved.

From the words you use it sounds like you are using the standard argument that the Cantor set consists of all ternary numbers expanded as decimals that do not contain the digit "1" Obviously, that set has the same cardinality as the reals using Cantor's diagonalization.
 
If I post it as a JPEG or BMP or other graphics file, will I still have to wait for this pending approval stuff?

Wrong dimensions! Hate image crap, what with the "waiting for approval" stuff ? Manual content approval or what?
 
Last edited:
OK, so its no longer pending approval (and I have gotten some sleep). Please respond soon, this is due in the morning.

Thanks,
-Ben
 
Last edited:
FYI, Theorem 2.20 (e) states that to every linear transformation [tex]T:\mathbb{R}^{k}\rightarrow\mathbb{R}^{k}[/tex] there exists a real number [tex]\Delta \left( T\right)[/tex] such that [tex]m\left( T\left( A\right) \right) = \Delta \left( T\right) m\left( A\right)[/tex] for every Lebesgue measurable set A.
 
How do you know that the Cantor set actually has a Lebesgue measure? Beyond that, the proof looks OK.
 

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