摘要：This article presents four experiments and a corpus study that have investigated 3-verb clusters with the verb lassen in the perfect tense. The prototypical 3-verb cluster with perfect tense lassen deviates from the normal pattern of verb-cluster formation in German in the same way as modal verbs: the perfect auxiliary occurs in cluster-initial position (auxiliary inversion) and lassen appears as a bare infinitive instead of the expected past participle (infinitivus pro participio (IPP) – „Ersatzinfinitiv“). In contrast to modal verbs, there is no agreement in the syntactic literature of whether auxiliary inversion and IPP are optional or obligatory for lassen. Four experiments obtaining grammaticality judgments under conrolled conditions revealed that IPP is obligatory but auxiliary inversion optional for causative lassen; for non-causative lassen (lassen in combination with verbs like fallen ‘to fall’ or liegen ‘to lay’), IPP and auxiliary inversion are both optional. A corpus study of the deWac corpus of German internet texts confirmed the experimental resul.
