How about ANY FINITE SEQUENCE AT ALL?

  • lily33@lemm.ee
    link
    fedilink
    arrow-up
    1
    ·
    edit-2
    2 months ago

    It’s almost sure to be the case, but nobody has managed to prove it yet.

    Simply being infinite and non-repeating doesn’t guarantee that all finite sequences will appear. For example, you could have an infinite non-repeating number that doesn’t have any 9s in it. But, as far as numbers go, exceptions like that are very rare, and in almost all (infinite, non-repeating) numbers you’ll have all finite sequences appearing.

  • AbouBenAdhem@lemmy.world
    link
    fedilink
    English
    arrow-up
    1
    ·
    edit-2
    2 months ago

    A number for which that is true is called a normal number. It’s proven that almost all real numbers are normal, but it’s very difficult to prove that any particular number is normal. It hasn’t yet been proved that π is normal, though it’s generally assumed to be.

    • db0@lemmy.dbzer0.com
      link
      fedilink
      arrow-up
      0
      arrow-down
      1
      ·
      edit-2
      2 months ago

      Thats very cool. It brings to mind some sort of espionage where spies are exchanging massive messages contained in 2 numbers. The index and the Metadata length. All the other spy has to do is pass it though pifs to decode. Maybe adding some salt as well to prevent someone figuring it out.

    • BrainInABox@lemmy.ml
      link
      fedilink
      English
      arrow-up
      0
      ·
      2 months ago

      Are you trying to say the answer to their question is no? Because if so, you’re wrong, and if not I’m not sure what you’re trying to say.

      • ped_xing [he/him]@hexbear.net
        link
        fedilink
        English
        arrow-up
        0
        ·
        2 months ago

        The conclusion does not follow from the premises, as evidenced by my counterexample. It could be the case that every finite string of digits appears in the decimal expansion of pi, but if that’s the case, a proof would have to involve more properties than an infinite non-repeating decimal expansion. I would like to see your proof that every finite string of digits appears in the decimal expansion of pi.

        • BrainInABox@lemmy.ml
          link
          fedilink
          English
          arrow-up
          0
          ·
          2 months ago

          Well that’s just being pointlessly pedantic, obviously they fucking know that a repeating number of all zeros and ones doesn’t have a two in it. This is pure reddit pedantry you’re doing

  • juliebean@lemm.ee
    link
    fedilink
    arrow-up
    0
    ·
    2 months ago

    no. it merely being infinitely non-repeating is insufficient to say that it contains any particular finite string.

    for instance, write out pi in base 2, and reinterpret as base 10.

    11.0010010000111111011010101000100010000101...
    

    it is infinitely non-repeating, but nowhere will you find a 2.

    i’ve often heard it said that pi, in particular, does contain any finite sequence of digits, but i haven’t seen a proof of that myself, and if it did exist, it would have to depend on more than its irrationality.

    • tetris11@lemmy.ml
      link
      fedilink
      arrow-up
      0
      ·
      2 months ago

      Isnt this a stupid example though, because obviously if you remove all penguins from the zoo, you’re not going to see any penguins

      • Lanthanae@lemmy.blahaj.zone
        link
        fedilink
        arrow-up
        0
        ·
        2 months ago

        Its not stupid. To disprove a claim that states “All X have Y” then you only need ONE example. So, as pick a really obvious example.

        • Umbrias@beehaw.org
          link
          fedilink
          arrow-up
          0
          ·
          2 months ago

          it’s not a good example because you’ve only changed the symbolic representation and not the numerical value. the op’s question is identical when you convert to binary. thir is not a counterexample and does not prove anything.

          • orcrist@lemm.ee
            link
            fedilink
            arrow-up
            0
            ·
            2 months ago

            Please read it all again. They didn’t rely on the conversion. It’s just a convenient way to create a counterexample.

            Anyway, here’s a simple equivalent. Let’s consider a number like pi except that wherever pi has a 9, this new number has a 1. This new number is infinite and doesn’t repeat. So it also answers the original question.

            • Umbrias@beehaw.org
              link
              fedilink
              arrow-up
              0
              ·
              2 months ago

              “please consider a number that isnt pi” so not relevant, gotcha. it does not answer the original question, this new number is not normal, sure, but that has no bearing on if pi is normal.

              • spireghost@lemmy.zip
                link
                fedilink
                English
                arrow-up
                0
                ·
                edit-2
                2 months ago

                OK, fine. Imagine that in pi after the quadrillionth digit, all 1s are replaced with 9. It still holds

      • untorquer@lemmy.world
        link
        fedilink
        arrow-up
        0
        ·
        2 months ago

        The explanation is misdirecting because yes they’re removing the penguins from the zoo. But they also interpreted the question as to if the zoo had infinite non-repeating exhibits whether it would NECESSARILY contain penguins. So all they had to show was that the penguins weren’t necessary.

        By tying the example to pi they seemed to be trying to show something about pi. I don’t think that was the intention.

        • juliebean@lemm.ee
          link
          fedilink
          arrow-up
          1
          ·
          2 months ago

          i just figured using pi was an easy way to acquire a known irrational number, not trying to make any special point about it.

          • untorquer@lemmy.world
            link
            fedilink
            arrow-up
            1
            ·
            2 months ago

            Yeah i got confused too and saw someone else have the same distraction.

            It makes sense why you chose that.

            This kind of thing messed me up so much in school 😂