Relative clauses in South Slavic and the predictability of morphosyntactic features

The paper investigates the morphosyntactic properties of relative markers in South Slavic. In Slavic languages, like in many other European languages, relative clauses can be introduced by two kinds of relative markers: (i) relative complementisers, which are invariant in their form, and (ii) relative pronouns, which are inflected (for case, number, and gender, depending on the language). Slavic languages regularly use wh-based complementisers and/or pronouns. Crucially, the two cannot co-occur: this ban is not grounded in the syntactic structure per se, but it derives from the feature incompatibility of two wh-based relative markers, which are regularly equipped with an uninterpretable relative feature. The only exception is Macedonian: in this case, however, there is independent evidence for the complementiser to have different features, suggesting that while morphological properties are good predictors for the relevant syntactic constraints, they are not deterministic.