Integrating Syntactic and Prosodic Information for the Efficient Detection of Empty Categories

We describe a number of experiments that demonstrate the usefulness of prosodic information for a processing module which parses spoken utterances with a feature-based grammar employing empty categories. We show that by requiring certain prosodic properties from those positions in the input where the presence of an empty category has to be hypothesized, a derivation can be accomplished more efficiently. The approach has been implemented in the machine translation project VERBMOBIL and results in a significant reduction of the work-load for the parser.Comment: To appear in the Proceedings of Coling 1996, Copenhagen. 6 page

Follow-up question handling in the IMIX and Ritel systems: A comparative study

One of the basic topics of question answering (QA) dialogue systems is how follow-up questions should be interpreted by a QA system. In this paper, we shall discuss our experience with the IMIX and Ritel systems, for both of which a follow-up question handling scheme has been developed, and corpora have been collected. These two systems are each other's opposites in many respects: IMIX is multimodal, non-factoid, black-box QA, while Ritel is speech, factoid, keyword-based QA. Nevertheless, we will show that they are quite comparable, and that it is fruitful to examine the similarities and differences. We shall look at how the systems are composed, and how real, non-expert, users interact with the systems. We shall also provide comparisons with systems from the literature where possible, and indicate where open issues lie and in what areas existing systems may be improved. We conclude that most systems have a common architecture with a set of common subtasks, in particular detecting follow-up questions and finding referents for them. We characterise these tasks using the typical techniques used for performing them, and data from our corpora. We also identify a special type of follow-up question, the discourse question, which is asked when the user is trying to understand an answer, and propose some basic methods for handling it

Overrated gaps: Inter-speaker gaps provide limited information about the timing of turns in conversation

Corpus analyses have shown that turn-taking in conversation is much faster than laboratory studies of speech planning would predict. To explain fast turn-taking, Levinson and Torreira (2015) proposed that speakers are highly proactive: They begin to plan a response to their interlocutor's turn as soon as they have understood its gist, and launch this planned response when the turn-end is imminent. Thus, fast turn-taking is possible because speakers use the time while their partner is talking to plan their own utterance. In the present study, we asked how much time upcoming speakers actually have to plan their utterances. Following earlier psycholinguistic work, we used transcripts of spoken conversations in Dutch, German, and English. These transcripts consisted of segments, which are continuous stretches of speech by one speaker. In the psycholinguistic and phonetic literature, such segments have often been used as proxies for turns. We found that in all three corpora, large proportions of the segments comprised of only one or two words, which on our estimate does not give the next speaker enough time to fully plan a response. Further analyses showed that speakers indeed often did not respond to the immediately preceding segment of their partner, but continued an earlier segment of their own. More generally, our findings suggest that speech segments derived from transcribed corpora do not necessarily correspond to turns, and the gaps between speech segments therefore only provide limited information about the planning and timing of turns

Hybrid discourse modeling and summarization for a speech-to-speech translation system

The thesis discusses two parts of the speech-to-speech translation system VerbMobil: the dialogue model and one of its applications, multilingual summary generation. In connection with the dialogue model, two topics are of special interest: (a) the use of a default unification operation called overlay as the fundamental operation for dialogue management; and (b) an intentional model that is able to describe intentions in dialogue on five levels in a language-independent way. Besides the actual generation algorithm developed, we present a comprehensive evaluation of the summarization functionality. In addition to precision and recall, a new characterization - confabulation - is defined that provides a more precise understanding of the performance of complex natural language processing systems.Die vorliegende Arbeit behandelt hauptsächlich zwei Themen, die für das VerbMobil-System, ein Übersetzungssystem gesprochener Spontansprache, entwickelt wurden: das Dialogmodell und als Applikation die multilinguale Generierung von Ergebnissprotokollen. Für die Dialogmodellierung sind zwei Themen von besonderem Interesse. Das erste behandelt eine in der vorliegenden Arbeit formalisierte Default-Unifikations-Operation namens Overlay, die als fundamentale Operation für Diskursverarbeitung dient. Das zweite besteht aus einem intentionalen Modell, das Intentionen eines Dialogs auf fünf Ebenen in einer sprachunabhängigen Repräsentation darstellt. Neben dem für die Protokollgenerierung entwickelten Generierungsalgorithmus wird eine umfassende Evaluation zur Protokollgenerierungsfunktionalität vorgestellt. Zusätzlich zu "precision" und "recall" wird ein neues Maß - Konfabulation (Engl.: "confabulation") - vorgestellt, das eine präzisere Charakterisierung der Qualität eines komplexen Sprachverarbeitungssystems ermöglicht