The evolution of the lexical richness of the Russian language (corpus research based on diachronic datasets from the national corpus of the Russian language)

Background. The relevance of this study is determined by the need to investigate lexical change in Russian using modern methods. The scientific novelty of the work lies in the development and application of complex statistical models and indices for a systematic quantitative analysis of Russian lexis based on new, previously unexplored material — frequency dictionaries for the periods 1700–1916, 1918–1991, and 1992–2016, with a total size of 250 million tokens. This made it possible to identify and quantitatively describe the dynamics of lexical richness and the structure of the vocabulary in a diachronic perspective. Purpose. To determine the specific features of the dynamics of lexical richness in Russian on the basis of frequency dictionaries for the periods 1700–1916, 1918–1991, and 1992–2016. Materials and methods. The material of the study consists of diachronic datasets of the Russian National Corpus for the periods 1700–1916, 1918–1991, and 1992–2016. The methods include computer‑based corpus processing and testing for compliance with Zipf’s law, calculation of the Herfindahl–Hirschman Index (HHI), Simpson’s index, Berger–Parker index, Shannon entropy, the Type–Token Ratio (TTR) as a coefficient of lexical diversity, chi‑square tests of statistical significance, and other related measures. Results. Corpus‑based analysis of diachronic data for the periods 1700–1916, 1918–1991, and 1992–2016 revealed a decrease in the overall lexical diversity and richness of Russian from the pre‑revolutionary to the post‑Soviet period. However, this lexical impoverishment occurs mainly at the expense of rare and low‑frequency words, whereas the active vocabulary, by contrast, expands and becomes more productive.