Rank-frequency distribution of natural languages: a difference of probabilities approach
The time variation of the rank k of words for six Indo-European languages is obtained using data from Google Books. For low ranks the distinct languages behave differently, maybe due to syntaxis rules, whereas for k>50 the law of large numbers predominates. The dynamics of k is described stochastically through a master equation governing the time evolution of its probability density, which is approximated by a Fokker-Planck equation that is solved analytically. The difference between the data and the asymptotic solution is identified with the transient solution, and good agreement is obtained.
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