this post was submitted on 21 Jun 2025
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Math Memes

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[–] fargeol@lemmy.world 55 points 1 day ago (4 children)

Theorem - All numbers are interesting

Demonstration:

  • 0 is interesting
  • if n is interesting, n+1 is either interesting or not interesting.
    -- If n+1 is not interesting, we take interest in it as it it the smallest non-interesting number.
  • Therefore, n+1 is interesting

By induction, all numbers are interesting

[–] CompassRed@discuss.tchncs.de 5 points 19 hours ago* (last edited 19 hours ago)

My favorite version of this proof:

Let S be the subset of natural numbers that are not interesting. Suppose by way of contradiction that S is inhabited. Then by the well ordering principle of natural numbers, there is a least such element, s in S. In virtue of being the least non interesting number, s is in fact interesting. Hence s is not in S. Since s is in S and not in S, we have derived a contradiction. Therefore our assumption that S is inhabited must be false. Thus S is empty and there are no non interesting numbers.

Counterproof:

n+1 is not the smallest non-interesting number... n-1 is.

what about the real, non-rational numbers?

[–] match@pawb.social 2 points 1 day ago (1 children)

What about 31? That's the smallest non-interesting number so if we take that as the first n, then every n+1 is either interesting or the second-smallest non-interesting number, and the second smallest non-interesting number is still not interesting.

[–] Stillwater@sh.itjust.works 9 points 1 day ago

31 is prime, that's interesting isn't it?