LF complex predicate formation: the case of participle fronting in Serbo-Croatian

We argue that cases of so-called long head movement in Serbo-Croatian, in which a participle precedes an auxiliary, involve complex predicate formation in covert syntax (LF). Following Wilder & Ćavar (1994) and Bo.ković (1995, 2001), we analyse these cases not as involving actual long head movement, but rather as head-to-head adjunction of the lower verb to the higher (verb clustering). Contrary to what these authors assume, however, we argue that, exceptionally, it is the participle that is merged as the higher verb, the auxiliary as the lower one. The auxiliary adjoins to the participle at LF. Any arguments can be licensed by the thematic properties of the participle, despite being merged in a lower phrase, as a result of the formation of a complex predicate consisting of participle and auxiliary at LF, the level where the theta-criterion is checked. This analysis provides an explanation for the verb clustering that does not occur in general in Serbo-Croatian, and makes possible a straightforward account of the word order possibilities in cases of verbal complexes with three verbs, of the fact that elements that are high in the structure block participle fronting whereas elements that are lower in the structure do not, and of certain gapping data.