Jouitteau (2012a)

• Jouitteau, M. 2012. 'Verb doubling in Breton and Gungbe; obligatory exponence at the sentence level’, The Morphosyntax of Reiteration in Creole and Non-Creole Languages, Aboh, Enoch O., Norval Smith and Anne Zribi-Hertz (éds.) [CLL 43]

 Breton tensed verbs show a synthetic/analytic alternation (I.know vs. to.know I.do), 
 that is not conditioned by their semantic or aspectual structure but by their syntactic 
 environment, namely word order. Such a paradigm of verb-doubling poses a strong case 
 against iconicity, because knowing where a verb can double requires full information 
 about the entire derivation of the sentence.
 The sentence is correct if and only if the tensed element is not at the left edge of the
 sentence. The infinitive form of the analytic construction prevents the tensed element 
 from occurring in the most left-edge position.
 This paper proposes that the analytic structure (to.know I.do) responds to the same 
 trigger as expletive insertion (expl I.know). I claim that analytic tense formation is a
 last resort strategy that forms the equivalent of an expletive by excorporation of the verbal
 root out of the tensed complex head. The excorporated lexical verb appears 
 fronted as an infinitive form by default. The tensed auxiliary is either realized as a
 dummy 'do' auxiliary (to.know I.do), or, for an idiosyncratic list of verbs, as the 
 tensed reiteration of the excorporated verb itself (doubling; to.know I.know)