Since Pi is infinite and non-repeating, would that mean any finite sequence of non-repeating numbers should appear somewhere in Pi?
Since Pi is infinite and non-repeating, would that mean any finite sequence of non-repeating numbers should appear somewhere in Pi?
How about ANY FINITE SEQUENCE AT ALL?
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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.
Isnt this a stupid example though, because obviously if you remove all penguins from the zoo, you're not going to see any penguins
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.
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.
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.
"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.
OK, fine. Imagine that in pi after the quadrillionth digit, all 1s are replaced with 9. It still holds
"ok fine consider a number that still isn't pi, it still holds." ??
Prove that said number isn't pi.
isnt, qed
Hmm, ok. Let me retry.
The digits of pi are not proven to be uniform or randomly distributed according to any pattern.
Pi could have a point where it stops having 9's at all.
If that's the case, it would not contain all sequences that contain the digit 9, and could not contain all sequences.
While we can't look at all the digits of Pi, we could consider that the uniform behavior of the digits in pi ends at some point, and wherever there would usually be a 9, the digit is instead a 1. This new number candidate for pi is infinite, doesn’t repeat and contains all the known properties of pi.
Therefore, it is possible that not any finite sequence of non-repeating numbers would appear somewhere in Pi.
They didn't convert anything to anything, and the 1.010010001... number isn't binary
then it's not relevant to the question as it is not pi.
The question is
Since pi is infinite and non-repeating, would it mean...
Then the answer is mathematically, no. If X is infinite and non-repeating it doesn't.
If a number is normal, infinite, and non-repeating, then yes.
To answer the real question "Does any finite sequence of non-repeating numbers appear somewhere in Pi?"
The answer depends on if Pi is normal or not, but not necessarily
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.
i just figured using pi was an easy way to acquire a known irrational number, not trying to make any special point about it.
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 😂
It does contain a 2 though? Binary ‘10’ is 2, which this sequence contains?
They also say "and reinterpret in base 10". I.e. interpret the base 2 number as a base 10 number (which could theoretically contain 2,3,4,etc). So 10 in that number represents decimal 10 and not binary 10
I don’t think the example given above is an apples-to-apples comparison though. This new example of “an infinite non-repeating string” is actually “an infinite non-repeating string of only 0s and 1s”. Of course it’s not going to contain a “2”, just like pi doesn’t contain a “Y”. Wouldn’t a more appropriate reframing of the original question to go with this new example be “would any finite string consisting of only 0s and 1s be present in it?”
They just proved that "X is irrational and non-repeating digits -> can find any sequence in X", as the original question implied, is false. Maybe pi does in fact contain any sequence, but that wouldn't be because of its irrationality or the fact that it's non-repeating, it would be some other property
Then put 23456789 at the start. Doesn't contain 22 then but all digits in base 10.
that number is no longer pi… this is like answering the question "does the number "3548" contain 35?" by answering "no, 6925 doesnthave 35. qed"
It was just an example of an infinite, non-repeating number that still does not contain every other finite number
Another example could be 0.10100100010000100000... with the number of 0's increasing by one every time. It never repeats, but it still doesn't contain every other finite number.
op's question was focued very clearly on pi, but sure.
this is correct but i think op is asking the wrong question.
at least from a mathematical perspective, the claim that pi contains any finite string is only a half-baked version of the conjecture with that implication. the property tied to this is the normality of pi which is actually about whether the digits present in pi are uniformly distributed or not.
from this angle, the given example only shows that a base 2 string contains no digits greater than 1 but the question of whether the 1s and 0s present are uniformly distributed remains unanswered. if they are uniformly distributed (which is unknown) the implication does follow that every possible finite string containing only 1s and 0s is contained within, even if interpreted as a base 10 string while still base 2. base 3 pi would similarly contain every possible finite string containing only the digits 0-2, even when interpreted in base 10 etc. if it is true in any one base it is true in all bases for their corresponding digits