Abstract
This paper illustrates how enriched diachronic treebank data can shed new light on an old and vexed topic, even when that topic is
primarily morphological and semantic in nature rather than syntactic. The topic is the rise of the Russian po
delimitatives, a change seen as crucial in most accounts of the history of Russian aspect, since it represents a major step in
generalising the derivational aspect system. Earlier accounts concur that the po delimitatives spread fairly
recently, too recently for the development to be connected to the loss of the aorist tense, which also had delimitative readings
with atelic verbs. Using treebank data from the Tromsø Old Russian and Old Church Slavonic Treebank, enriched with tags for
derivational morphology and semantics, I show that the po delimitatives were not marginal even in the earliest
Slavic sources, either in terms of frequency or semantics, and that they first complemented and then competed with the
delimitative aorists. It can thus be claimed that the exotic po delimitatives grew organically out of the old
Indo-European inflectional aspect system.
A Graph Auto-encoder Model of Derivational Morphology
