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We predict discourse segment boundaries from linguistic features of utterances, using a corpus of spoken narratives as data. We present two methods for developing segmentation algorithms from training data: hand tuning and machine learning. When multiple types of features are used, results approach human performance on an independent test set (both methods), and using cross-validation (machine learning).

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This paper presents an analysis of purpose clauses in the context of instruction understanding. Such analysis shows that goals affect the interpretation and / or execution of actions, lends support to the proposal of using generation and enablement to model relations between actions, and sheds light on some inference processes necessary to interpret purpose clauses.

We here explore a "fully" lexicalizod Tree-Adjoining Grammar for discourse that takes the basic ele- ments of a (monologic) discourse to be not simply clauses, but larger structures that are anchored on variously realized discourse cues This link with intra-sentential grammar suggests an account for different patterns of discourse cues. while the different structures and operations suggest three sepa- rate sources for elements of discourse meaning: (1) a compositional semantics tied to the basic trees and operations; (2) a presuppositional semantics carried by cue phrases that freely adjoin to trees; and (3) general inference, that draws additional, defensible conclusions that flesh out what is conveyed compositionally.

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In this paper we discuss some requirements on natural language interfaces that are needed for supporting connected dialogue, and propose methods for meeting these requirements in the context of a system that has been developed at our department over the last couple of years. On the basis of data collected in Wizard-of-Oz simulations we argue that the dynamic discourse representation needed for a given application can be structured in terms of a tree of dialogue objects (moves, initiativeresponse units) and a score board, i.e. a list of parameters each of which keeps some information relevant to the system's interpretation and generation tasks. We also argue that the domain knowledge needed for supporting reference resolution can, and should be obtained from data of this kind. 1

In this paper, we present the results of a corpus analysis, and a model of anaphora resolution in spontaneous spoken dialogues in the form of an algorithm. The main finding of our corpus analysis is that less than half the pronouns and demonstratives have NP antecedents in the preceding text. 22% have sentential antecedents and the remainder have no identifiable linguistic antecedents. As part of the corpus analysis we present the results of interannotator agreement tests. These were carried out for marking anaphor types and their antecedents, and for segmenting the dialogues into dialogue acts. The results of the inter-annotator agreement tests indicate that our classification method is reliable and that the annotated dialogues can be used as a standard against which to measure the performance of the resolution algorithm. The algorithm, based on Strube (1998), is capable of classifying pronouns and demonstratives, and co-indexing anaphors with NP and sentential antecedent...

In this thesis, we present analyses and algorithms for resolving a variety of cohesive phenomena in natural language, including VP-ellipsis, gapping, event reference, tense, and pronominal reference. Past work has attempted to explain the complicated behavior of these expressions with theories that operate within a single module of language processing. We argue that such approaches cannot be maintained; in particular, the data we present strongly suggest that the nature of the coherence relation operative between clauses needs to be taken into account. We provide a theory of coherence relations and the discourse inference processes that underly their recognition. We utilize this theory to break the deadlock between syntactic and semantic approaches to resolving VP-ellipsis. We show that the data exhibits a pattern with respect to our categorization of coherence relations, and present an account which predicts this pattern. We extend our analysis to gapping and event reference, and sho...

NULL vs. OVERT SUBJECTS IN TURKISH DISCOURSE: A CENTERING APPROACH Author: Umit Deniz Turan Supervisor: Ellen F. Prince The purpose of this study is to explore an aspect of discourse coherence which involves anaphoric relations between utterances with special emphasis on subjects in Turkish. Based on an analysis of published narratives, three complementary and interrelated questions are addressed concerning discourse anaphora: 1. Which expressions are available for subsequent definite reference? 2. What factors determine the most salient entity in Turkish among a set of potential antecedents for subsequent definite reference? 3. What are the functions of a particular referential expression (null vs. overt pronouns vs. full NPs), depending on appropriate discourse conditions? An exploration regarding question 1 indicates that, while some NPs evoke discourse entities, other NPs do not. These two types of NPs represent referential and nonreferential expressions and they can function as ...