A temporal analysis for 'irrealis' zai

The Mandarin Chinese adverb ZAI, in its adverbial use, displays a number of peculiarities--concerning the temporal orientation of the predicate, its aspectual properties and the syntactic/logical role of the sentence where it occurs--which, as a whole, have been subsumed under the feature 'irrealis'. In this paper, we consider ZAI as an additive particle in the domain of events and we propose to derive its 'irrealis' flavour from constraints on the structure and temporal location of the asserted event. As an additive particle, ZAI conveys a presupposition which cannot be recovered indipendently from the context of occurrence