01729nas a2200181 4500008004100000245007900041210006900120260003400189300001300223490000700236520115000243100002001393700001801413700002301431700001901454700002101473856005301494 2015 eng d00aRank Diversity of Languages: Generic Behavior in Computational Linguistics0 aRank Diversity of Languages Generic Behavior in Computational Li bPublic Library of Sciencec04 ae01218980 v103 a
Statistical studies of languages have focused on the rank-frequency distribution of words. Instead, we introduce here a measure of how word ranks change in time and call this distribution rank diversity. We calculate this diversity for books published in six European languages since 1800, and find that it follows a universal lognormal distribution. Based on the mean and standard deviation associated with the lognormal distribution, we define three different word regimes of languages: “heads” consist of words which almost do not change their rank in time, “bodies” are words of general use, while “tails” are comprised by context-specific words and vary their rank considerably in time. The heads and bodies reflect the size of language cores identified by linguists for basic communication. We propose a Gaussian random walk model which reproduces the rank variation of words in time and thus the diversity. Rank diversity of words can be understood as the result of random variations in rank, where the size of the variation depends on the rank itself. We find that the core size is similar for all languages studied.
1 aCocho, Germinal1 aFlores, Jorge1 aGershenson, Carlos1 aPineda, Carlos1 aSánchez, Sergio uhttp://dx.doi.org/10.1371%2Fjournal.pone.0121898