Presupposition Resolution With Discourse Information Structures

An approach to resolving a number of presuppositional phenomena, including definite descriptions and pronominal anaphora, is described within the larger context of an architecture for query-based, task-oriented human/computer dialogue. The model of discourse context employed assumes that discourse structure is organized around a stack of questions under discussion, which plays an important role in narrowing the search space for referents and other presupposed information. The algorithms of individual presuppositional operators for maintaining discourse structures are presented and illustrated in several example dialogues in which human users interact with an agent in order to make hotel reservations. The overall architecture is compared to SDRT (Segmented Discourse Representation Theory), in terms of efficiency and ease of implementation

Towards a Computational Model of Anaphora in Discourse: Reference to Events and Actions

When people talk or write, they refer to things, objects, events, actions, facts and/or states that have been mentioned before. Such context-dependent reference is called anaphora. In general, linguists and researchers working in artificial intelligence have looked at the problem of anaphora interpretation as that one of finding the correct antecedent for anaphor - that is, the previous words or phrases to which the anaphor is linked. Lately, people working in the area of anaphora have suggested that in order for anaphors to be interpreted correctly, they must be interpreted by reference to entities evoked by the previous discourse rather than in terms of their antecedents. In this recent work, people have focused on entities of type concrete individual (an x) or set of such individuals (some xs) or generic class of such individuals (xs). This proposal focuses on anaphora interpreted as referring to entities of type event and action. It considers four issues: (i) what aspects of the discourse give evidence of the events and actions the speaker is talking about, (ii) how actions and events are represented in the listener\u27s discourse model, (iii) how to delimit the set of events and actions which correspond to possible choices for a particular anaphor, and (iv) how to obtain the speaker\u27s intended referent to an action or event from that set of possible choices. Anaphoric forms that are used to refer to entities of type action and event include sentential-it, sentential-that pronominalizations as well as do it, do that, and do this forms. I will concentrate on the four previously mentioned issues along with other mechanisms that will provide us with better tools for the successful interpretation of anaphoric reference in discourse

CLiFF Notes: Research In Natural Language Processing at the University of Pennsylvania

CLIFF is the Computational Linguists\u27 Feedback Forum. We are a group of students and faculty who gather once a week to hear a presentation and discuss work currently in progress. The \u27feedback\u27 in the group\u27s name is important: we are interested in sharing ideas, in discussing ongoing research, and in bringing together work done by the students and faculty in Computer Science and other departments. However, there are only so many presentations which we can have in a year. We felt that it would be beneficial to have a report which would have, in one place, short descriptions of the work in Natural Language Processing at the University of Pennsylvania. This report then, is a collection of abstracts from both faculty and graduate students, in Computer Science, Psychology and Linguistics. We want to stress the close ties between these groups, as one of the things that we pride ourselves on here at Penn is the communication among different departments and the inter-departmental work. Rather than try to summarize the varied work currently underway at Penn, we suggest reading the abstracts to see how the students and faculty themselves describe their work. The report illustrates the diversity of interests among the researchers here, as well as explaining the areas of common interest. In addition, since it was our intent to put together a document that would be useful both inside and outside of the university, we hope that this report will explain to everyone some of what we are about

Coreference resolution survey

This survey is an extended summarization of state of the art of coreference resolution. The key concepts related to coreference and anaphora are presented, the most relevant approaches to coreference resolution are discussed, and existing systems are classified and compared. Finally, the evaluation methods shared by researchers in the area and the commonly used data sets corpora are presented and compared.Postprint (published version

Information structure and the referential status of linguistic expression : workshop as part of the 23th annual meetings of the Deutsche Gesellschaft für Sprachwissenschaft in Leipzig, Leipzig, February 28 - March 2, 2001

This volume comprises papers that were given at the workshop Information Structure and the Referential Status of Linguistic Expressions, which we organized during the Deutsche Gesellschaft für Sprachwissenschaft (DGfS) Conference in Leipzig in February 2001. At this workshop we discussed the connection between information structure and the referential interpretation of linguistic expressions, a topic mostly neglected in current linguistics research. One common aim of the papers is to find out to what extent the focus-background as well as the topic-comment structuring determine the referential interpretation of simple arguments like definite and indefinite NPs on the one hand and sentences on the other

Generating referring expressions in a domain of objects and processes

This thesis presents a collection of algorithms and data structures for the generation of pronouns, anaphoric definite noun phrases, and one-anaphoric phrases. After a close analysis of the particular kinds of referring expressions that appear in a particular domain -that of cookery recipes -the thesis presents an appropriate ontology and a corresponding representation language. This ontology is then integrated into a wider framework for language generation as a whole, whereupon we show how the representation language can be successfully used to produce appropriate referring expressions for a range of complex object types.Amongst the more important ideas explored in the thesis are the following:• We introduce the notion of a generalized physical object as a way of representing singular entities, mass entities, and entities which are sets.• We adopt the view that planning operators are essentially underspecified events, and use this, in conjunction with a simple model of the hearer, to allow us to determine the appropriate level of detail at which a given plan should be described.• We make use of a discourse model that distinguishes local and global focus, and is closely tied to a notion of discourse structure; and we introduce a notion of DISCRIMINATORY POWER as a means to choosing the content of a referring expression.• We present a model of the generation of referring expressions that makes use of two levels of intermediate representation, and integrate this model with the use of a linguistically- founded grammar for noun phrases.The thesis ends by making some suggestions for further extensions to the work reported here

Making Worlds Accessible. Essays in Honor of Angelika Kratzer

Every linguist knows how colossal Angelika’s impact on our field is. Hearing aboutthis would not be informative for anybody who might (virtually) pick up this volume, including Angelika herself. So, instead of writing about, say, Angelika’s crucial role in the development of our understanding of modality, we will write about what Angelika means to us, as a teacher, advisor, mentor, colleague, and friend. We know that these words will resonate with many of you (Angelika has meant so much to so many people). We just get to be the lucky ones to tell Angelika publicly.https://scholarworks.umass.edu/ak_festsite_schrift/1000/thumbnail.jp

Representing Context: Presupposition Triggers and Focus-sensitivity

This dissertation investigates the role of Focus-sensitivity for a typology of presupposition triggers. The central hypothesis is that Focus-sensitive triggers require a linguistic antecedent in the discourse model, whereas presuppositions of triggers lacking Focus-sensitivity are satisfied as entailments of the Common Ground. This hypothesis is supported by experimental evidence from two borne out predictions. First, Focus-sensitive triggers are sensitive to the salience of the antecedent satisfying their presupposition, as operationalized via the Question Under Discussion, and lead to interference-type effects, while triggers lacking Focus-sensitivity are indifferent to the QUD-structure. Second, Focus-sensitive triggers are harder to globally accommodate than triggers lacking Focus-sensitivity. The picture that emerges from these results is that the same kind of meaning - presuppositions - is grounded in distinct underlying representations of context in relation to an independent property of the trigger - Focus-sensitivity - which directly affects the way a trigger is processed

Definiteness effects and competition in tenses and aspects

This dissertations explores the semantics and pragmatics of tense and aspect constructions in three groups of languages: I. English; II. French, Italian, German; III. Mandarin Chinese. The basic claims of this dissertation are: (i) the English past tense is lexically ambiguous between an anaphoric and a uniqueness reading; (ii) the different properties of the present perfect construction in English versus French, Italian and German follow from the competition between the present perfect with the alternative past tense and the different set of alternatives available in these languages; (iii) the distribution of the Mandarin Chinese perfective particles reflects asymmetry in their presuppositions, such as anaphoricity and anti-resultativeness; (iv) Mandarin Chinese differs from the languages in group I and II in that it establishes anaphoric dependency in the domain of eventualities, not times; (v) the crosslinguistic distribution of perfect-like tense-aspectual constructions follows from similar semantic-pragmatic strategies, namely the competition between alternatives from a set of general categories (anaphoric, unique, neutral, and antiresulative)

Semantic Ambiguity and Perceived Ambiguity

I explore some of the issues that arise when trying to establish a connection between the underspecification hypothesis pursued in the NLP literature and work on ambiguity in semantics and in the psychological literature. A theory of underspecification is developed `from the first principles', i.e., starting from a definition of what it means for a sentence to be semantically ambiguous and from what we know about the way humans deal with ambiguity. An underspecified language is specified as the translation language of a grammar covering sentences that display three classes of semantic ambiguity: lexical ambiguity, scopal ambiguity, and referential ambiguity. The expressions of this language denote sets of senses. A formalization of defeasible reasoning with underspecified representations is presented, based on Default Logic. Some issues to be confronted by such a formalization are discussed.Comment: Latex, 47 pages. Uses tree-dvips.sty, lingmacros.sty, fullname.st