Avar non-finites between restructuring and periphrasis

In many languages, forms traditionally characterised as nonfinite (participles, infinitives, converbs and gerunds/nominalisations) can either head a clausal constituent of their own or occur inside a periphrastic TAM-construction. Existing theoretical approaches to the morphosyntax of such elements postulate a range of mechanisms — both narrow-syntactic such as head movement and post-syntactic such as structure removal, impoverishment, underspecification or fusion — to enable the insertion of an identical form into two distinct syntactic structures. Using Avar (East Caucasian) as a test case, I review two main groups of approaches to verbal periphrasis and propose a tentative analysis.