релятивные конструкции, синтаксис, грамматикализация, русский язык, сербский язык, хорватский язык, боснийский язык, чешский язык, польский язык, словацкий язык, Slavic languages. Baltic languages. Albanian languages, PG1-9665

This paper presents the key points concerning Slavic relative constructions with a group of kindred invariable lexemes: Russian что, BCS što, Czech, Polish co, Slovak čo, and their cognates. These constructions are classified into two main types, depending on whether the third-person pronoun is used for marking the relative target. Across Slavic languages, the parameters governing the distribution between the two types are closely connected. The interpretation of these parameters (as well as their microvariation) is presented within the functional-typological approach. Syntactic category (part of speech) of the lexemes is discussed in diachronic perspective: in the more innovative construction with third-person pronoun, čto functions more as a complementizer; in the more conservative construction without the pronoun, čto retains some pronoun traits.