(11-04-2026, 11:55 AM)Rafal Wrote: You are not allowed to view links. Register or Login to view.Let's take a hypothetical long string of numbers 1-6 written in medieval book. We made calculations and observed that:
- all numbers have very similar frequencies
- there aren't any longer sequences repeating
In such case we can propose a scenario that it was probably generated by throwing a 6-walled dice.
That would be a
possibility but those observations do not prove it, and not even make it likely. The sequence of digits of Pi in base 6 has those properties too, but it is not random. (Same for sqrt(2), or the digits of most irrational real numbers in any base)
And if you take any text, even a very repetitive one, and encode it with the Vigenère cipher using the digits of Pi as the key, you will get a ciphertext that has those same properties too.
(When I was getting my Masters in applied math, a friend of mine was doing his thesis on a simple process for generating infinite strings that were "cube-free" -- that did not have substrings that repeat three times in a row. For instance the string 0010100110100110100110101 is not "cube-free" because it contains 010011 three times in a row. The problem was inspired by a rule of chess that declares a draw if the players repeat the same sequence of moves three times in a row.
I forgot the details, but it was something like this. You need at least three letters in the alphabet, say A, B, C. You start with a single A and then do repeated passes where each letters is replaced by a specific string of those three letters. Like A -> ABCA, B -> CA, C -> BAC. Thus you get A, then ABCA, then ABCACABAC, then ABCACABACABCABACABCACAABCABAC, etc. I just guessed these particular replacements and they probably don't work, but with the right rules one gets arbitrarily long strings that are cube-free. Possibly they have equal numbers of As, B, and Cs.
This "iterated verbose substitution cipher" process is very simple procedure that someone like Tartaglia or Fibonacci could have thought of and played around with, well before the 15th century. It is less complicated than the process that was used by the anonymous nerd who created those tables that baffled John Dee (although, AFAIK, those were probably created in the 16th century). The point is that it is actually easier to generate
non-random deterministic strings that "look random" under simple statistical test, than to generate truly random sequences...
At some point the other Masters students in the department gave that guy, as a birthday present, a fake Master's thesis, properly formatted and bound -- including with the official cardboard thesis cover, fake examiners' signatures, etc -- titled "The Problem of the Abacas"; with every one of its 100 pages filled with a random string of A, B, and C.)