Part 5/16:
Markov challenged this interpretation. He demonstrated that the law of large numbers could still hold even when events are dependent—a revolutionary idea in probability theory. To do this, he turned to analyzing language, specifically Russian poetry by Alexander Pushkin, to see if letter sequences follow the assumption of independence.
Markov examined the entire text of "Eugene Onegin," splitting it into overlapping pairs of letters. Instead of the expected 18% chance of vowels following vowels (assuming independence), he found only 6%. This discrepancy indicated that letter choices depend heavily on previous letters.