this post was submitted on 23 Oct 2024
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[โ€“] jsomae@lemmy.ml -2 points 3 weeks ago* (last edited 1 day ago) (3 children)

Your explanation is wrong. There is no reason to believe that "c" has no mapping.

Edit: for instance, it could map to 29, or -7.

[โ€“] CanadaPlus@lemmy.sdf.org 2 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

Yeah, OP seems to be assuming a continuous mapping. It still works if you don't, but the standard way to prove it is the more abstract "diagonal argument".

[โ€“] jsomae@lemmy.ml 1 points 1 day ago* (last edited 1 day ago)

But then a simple comeback would be, "well perhaps there is a non-continuous mapping." (There isn't one, of course.)

"It still works if you don't" -- how does red's argument work if you don't? Red is not using cantor's diagonal proof.

[โ€“] CileTheSane@lemmy.ca 2 points 3 weeks ago

Give me an example of a mapping system for the numbers between 1 and 2 where if you take the average of any 2 sequentially mapped numbers, the number in-between is also mapped.

[โ€“] red@lemmy.zip 1 points 2 weeks ago (1 children)

because I assumed continuous mapping the number c is between a and b it means if it has to be mapped to a natural number the natural number has to be between 22 and 23 but there is no natural number between 22 and 23 , it means c is not mapped to anything

[โ€“] jsomae@lemmy.ml 1 points 1 day ago* (last edited 1 day ago)

Then you did not prove that there is no discontiguous mapping which maps [1, 2] to the natural numbers. You must show that no mapping exists, continugous or otherwise.