Disambiguation by Information Structure in DRT

~i%xt understanding and high quality machine translation often necessitate the disambiguation of ambigous structures or lexical elements. Drawing inferences from the context can be a means for resolving semantic ambiguities. However, often, this is an ex-. pensive s trategy that, in addition, not always comes up with a clear preference for one of the alternatives. In this paper, we argue that in a number of cases deep semantic analyses can be avoided by taking into account the constraints that the alternative readings impose onto the information structure. To this end, we present a study of the arnbigous German adverb erst and point out the particular circumstances under which the given information structure disambiguates the adverb without further semantic analysis. 1 I n t r o d u c t i o n German erst is ambigous. Consider the following examples: (1) Peter zeigte erst auf die vierte Gliickszahl. a) Und dann auf die zweite. (Peter first pointed to the fourth lucky number. And then to the second.) b) Nicht zuvor auf die erste, zweite oder dlqtte. (Peter only pointed to the fourth lucky number. Not to the first, second or third.) c) Noeh nieht aufd ie Nnfte. (Peter only pointed to the fourth lucky number so far. Not yet to the fifth.) The alternative contexts a) e) determine the meaning of the first sentence of (1) according to *This paper describes research done within the Sonderforschunsbereich 3~0 at IMS. I would like to thank Anette Frank, Hans Kamp, Michael Schiehlen and the other members of the IMS semantics group for helpfull discussion. the disambiguating translations presented. ' rhe example testifies the following three uses of crsl: • In the context (1.a), the recipient understands the introduced event as the first of a sequence of events that he expects to be completed by the following text. We call this reading: the First of a Sequence-reading (FS). • In the context (1.b), the recipient understands erst as a signal of the speaker/wri ter that the occurrence of the reported event is not preceded by the occurrence of similar (alternative) events. We call this reading: the Exclusion of Preceding Alternatives-