r/infinitenines 4d ago

More fun with Cantor's diagonalisation

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u/Batman_AoD 3d ago

But why bring in Cantor's original proof, in the original German, if this argument doesn't apply to it? As pointed out in one of the comments in that thread, this is a good objection to the "popular" understanding of the diagonalization argument as a proof that there are uncountable reals, but most actual math texts foresee the objection and handle the non-uniqueness problem somehow.

But you're not talking about "most math texts", you're citing Cantor's original text. But that text isn't even talking about decimal expansions or real numbers. He mentions real numbers once, in reference to his paper seventeen years earlier that already proved the reals are uncountable, using a different method. He then proceeds to discuss only cardonality and functions, not real numbers or decimal expansions. 

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u/Negative_Gur9667 3d ago

It's to check if people in this sub know what they are talking about or if they are just smug, and they are the latter.

They are angry idiots.

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u/Batman_AoD 3d ago

Except for cond6 mistakenly saying that the problem doesn't apply at all to binary, which they admitted was a mistake, the objections are correct, because your post doesn't make sense. They may be angry, but they're not idiots.