INTERCHANGE О~А BEFORE THE SUFFIX -YVA
The purpose of this study is to identify patterns causing the interchange of O~A in the position before the suffix =YVA. The article describes 2290 Russian verbs that have or could have an O~A interchange in the syllable preceding the suffix =YVA. The authors propose six rules (two prescriptive and four blocking). Rule 1 (blocking): For non-mastery adopted stems interchange О~А before the suffix =YVA is not possible. Rule 2 (blocking): In a syllable OVinterchanging with Y, interchange O~A before =YVA is not possible. Rule 3 (prescriptive): The appearance of the stage a (after 1916 year) is necessarily if the last syllable of the originality or mastery unstressed pre-degree stem has in the infinitive O in combination with other power suffix (=У/=ё, =0, =ny). Rule 4 (blocking): The interchange O~A before =YVA is impossible if the verb contains the prefix complex o-bez-. Rule 5 (prescriptive): Interchange O~A before =YVA in the position before morphoneme {/} is necessarily in the non-stylizedtexts after 1924year. Rule 6 (blocking): The interchange O~A before =YVA in the originality/mastery word stem is impossible if as a result arises lexical ambiguity. The position before =YVA is an indicator of the originality/mastery or adopted/non-mastery of the word stem, as well as the relevance/irrelevance of some meanings. The article contains exceptions that indicate a conflict between usage and the norms of the literary language. An appeal to the Russian National Corpus allows setting chronological restrictions for some of the rules.