Syntactically well-formed sentences are not only generated according to the constraints of the syntactic component of grammar but also according to the requirements of the lexical component, which captures the relevant features of the predicates the syntax works on. The influence of the lexicon on the syntax reveals itself most clearly in the case of sentence-embedding predicates such as claim, ask, promise, refuse, seem, know, believe, be glad, etc. Among other things, differences seem to exist between predicates with respect to selectional restrictions (e.g. believe that vs. *believe whether), and possible control readings (e.g. x promises y to come → x will come; x persuades y to come → y should come).
The leading question of PB 3 is to what extent the syntax of embedded sentences is determined by the lexical specifications of sentence-embedding predicates, and to what extent the lexical properties of such predicates are influenced by syntactic properties of subordination structures. It is often hard to decide which of these factors is more prominent. The idea is that situations of language contact and change can provide an additional testing ground for these hypotheses about the interaction between the lexical and syntactic component of the grammar.
The area Diachrony of German sentence-embedding predicates investigates the historical development of sentence-embedding predicates and the differentiation of the inventory of such predicates from Old High German to New High German.
The area Sentence-embedding predicates in creole languages focuses on the possible changes in sentence-embedding predicates due to language contact. Owing to the extreme circumstances under which they arose, creoles are the result of intimate language contact between a superstrate language (typically a European language) and several substrate languages (e.g. West African languages). One of the leading questions in this area will be to what extent the syntactic and semantic properties of sentence-embedding predicates in creoles result from the superstrate or substrate languages, or whether these predicates developed their properties independently from general principles of syntactic computation and the syntax-semantics interface.
The area Status and realization of the sentential argument investigates two aspects of sentential embedding that have been relatively neglected up to now. First, by which means (Case/Adpositions) are sentential arguments licensed? Second, how are additional (sentential) arguments licensed? (cf. Frank hämmert Maria ein, dass sie sparen soll - Frank keeps dinging it into Maria that she should save money - vs. *Frank hämmert, dass Maria sparen soll - Frank hammers that Maria should save money).
Our research group uses a database for sentence-embedding predicates in which predicates of different languages and from diachronic stages are filed. This database makes it possible to search on the basis of predicate classes. Another goal is to document precisely the cross-linguistic variation of sentence-embedding predicates. One of our interests is to find out to what extent syntactically established predicate classes are determined semantically.