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Math Help - Countable Sets with repeated Elements

  1. #1
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    Countable Sets with repeated Elements

    (System won't let me respond to map (m,n) to N so I will address the issue involving the last reply here. Which is just as well as it's really a separate topic.

    Slipstream comment is valid. I did have a reservation about my post based on the following

    THE QUESTION:

    A={a,a,a} and B={a} have the same size (cardinality) based on the fact that they are the same sets. AsubB and BsubA.


    Are {a,a,a,a,........} and {a} the same size, ie, countable?
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  2. #2
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    Re: Countable Sets with repeated Elements

    Formally speaking the set \{a,a,a,\dots \} cannot be constructed using the rules of set theory. So technically speaking it is not a set.
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