Anaphora and Discourse Structure

We argue in this paper that many common adverbial phrases generally taken to signal a discourse relation between syntactically connected units within discourse structure, instead work anaphorically to contribute relational meaning, with only indirect dependence on discourse structure. This allows a simpler discourse structure to provide scaffolding for compositional semantics, and reveals multiple ways in which the relational meaning conveyed by adverbial connectives can interact with that associated with discourse structure. We conclude by sketching out a lexicalised grammar for discourse that facilitates discourse interpretation as a product of compositional rules, anaphor resolution and inference.Comment: 45 pages, 17 figures. Revised resubmission to Computational Linguistic

A Data-Driven Methodology for Motivating a Set of Coherence Relations

Institute for Communicating and Collaborative SystemsThe notion that a text is coherent in virtue of the `relations' that hold between its component spans currently forms the basis for an active research programme in discourse linguistics.Coherence relations feature prominently in many theories of discourse structure, and have recently been used with considerable success in text generation systems. However, while the concept of coherence relations is now common currency for discourse theorists there remains much confusion about them, and no standard set of relations has yet emerged. The aim of this thesis is to contribute towards the development of a standard set of relations. We begin from an explicitly empirical conception of relations: they are taken to model a collection of psychological mechanisms operative during the tasks of reading and writing.This conception is fleshed out with reference to psychological theories of skilled task performance, and to Rosch's notion of the basic level of categorisation. A methodology for investigating these mechanisms is then presented, which takes as its starting point a study of cue phrases- the sentence/clause connectives by which they are signaled. Although it is conventional to investigate psychological mechanisms by studying human behaviour, it is argued here that evidence for the constructs modelled by relations can be sought in ananalysis of the linguistic resources available for marking them explicitly intext. The methodology is based on two simple linguistic tests: the test for cue phrases and the test for substitutability. Both tests are functional in inspiration: the former test identifies a heterogenous class of phrases used for linking one portion of text to another; and the later test is used to discover when a writer is willing to substitute one of these phrases for another. The tests are designed to capture the judgements of ordinary readers and writers, rather than the theoretical intuitions of specialised discourse analysts. The test for cue phrases is used to analyse around 20 pages of naturally occuring text, from which a corpus of over 20 cue phrases is assembled. The substitutability test is then used to organise this corpus into a hierarchical taxonomy, representing the substitutability relationship between every pair of phrases. The taxonomy of cue phrases lends itself neatly to a model of relations as feature-based constructs. Many cue phrases can be interpreted as signalling just some features of relations, rather than whole relations. Small extracts from the taxonomy can be used systematically to determine the alternative values of single features; complex relation definitions can then be formed by combining the values of many features. The thesis delivers results on two levels. Firstly,it sets out a methodology for motivating a set of relation definitions, which rests on a systematic analysis of oncrete linguistic data, and demands a minimum of theoretical assumptions. Also provided are the relation definitions which result from applying the methodology. The new definitions give an interesting picture of the variation that exists amongst cuephrases, and offers a number of innovative insights into text coherence

A SENSORIMOTOR CHARACTERISATION OF SYNTAX, AND ITS IMPLICATIONS FOR MODELS OF LANGUAGE EVOLUTION

In this paper I consider the possibility that language is more strongly grounded in sensorimotor cognition than is normally assumed—a scenario which would be providential for language evolution theorists. I argue that the syntactic theory most compatible with this scenario, perhaps surprisingly, is generative grammar. I suggest that there may be a way of interpreting the syntactic structures posited in one theory of generative grammar (Minimalism) as descriptions of sensorimotor processing, and discuss the implications of this for models of language evolution. 1. An optimistic idea about how to study language evolution One way of studying language evolution is to investigate the interface between language and sensorimotor representations in modern humans. We know that there is an interface, of course, because we can talk about what we see and do in the world. But opinions vary about how much work is involved in converting sensorimotor signals into an utterance. If language is a Fodorian module, then a lot of work is involved, because there is no overlap between the sensorimotor mechanisms which create an episode representation and the syntactic mechanisms which express it as an utterance. But many cognitive scientists now argue that syntacti

Issues in Cue Phrase Implicature

Knott's empirical study of cue phrases has resulted in a taxonomic classification of some 150 cue phrases. The taxonomy can be viewed as a partial ordering on the set of phrases, and hence we can view cue phrase selection in terms of scalar implicature, following Hirschberg. We draw out some of the immediate consequences of this view, including the problematic status of the conventional/conversational distinction, and the proper treatment of high-level cue phrases. We conclude by considering how to test empirically some of the new predictions. Introduction The call for papers raised a number of questions, two of which we are directly addressing in new work: Coherence How does conversational implicature relate to other discourse phenomena, e.g., coherence and discourse expectations? Data Are there classes of discourse phenomena (e.g., ellipsis) which it would be advantageous to analyse as types of conversational implicature although they are not currently recognised as such in the co..

Anaphora and Discourse Semantics

We argue in this paper that many common adverbial phrases generally taken to be discourse connectives signalling discourse relations between adjacent discourse units are instead anaphors. We do this by (i) demonstrating their behavioral similarity with more common anaphors (pronouns and definite NPs); (ii) presenting a general framework for understanding anaphora into which they nicely fit; (iii) showing the interpretational benefits of understanding discourse adverbials as anaphors; and (iv) sketching out a lexicalised grammar that facilitates discourse interpretation as a product of compositional rules, anaphor resolution and inference

The impact of artificial intelligence on jobs and work in New Zealand

Artificial Intelligence (AI) is a diverse technology. It is already having significant effects on many jobs and sectors of the economy and over the next ten to twenty years it will drive profound changes in the way New Zealanders live and work. Within the workplace AI will have three dominant effects. This report (funded by the New Zealand Law Foundation) addresses: Chapter 1 Defining the Technology of Interest; Chapter 2 The changing nature and value of work; Chapter 3 AI and the employment relationship; Chapter 4 Consumers, professions and society. The report includes recommendations to the New Zealand Government

Discourse Relations: A Structural and Presuppositional Account Using Lexicalised TAG

We show that discourse structure need not bear the full burden of conveying discourse relations by showing that many of them can be explained nonstructurally in terms of the grounding of anaphoric presuppositions (Van der Sandt, 1992). This simplifies discourse structure, while still allowing the realisation of a full range of discourse relations. This is achieved using the same semantic machinery used in deriving clause-level semantics

Experiments Using Stochastic Search For Text Planning

Marcu has characterised an important and difficult problem in text planning: given a set of facts to convey and a set of rhetorical relations that can be used to link them together, how can one arrange this material so as to yield the best possible text? We describe experiments with a number of heuristic search methods for this task. 1 Introduction: Text Planning 1.1 The Task This paper presents some initial experiments using stochastic search methods for aspects of text planning. The work was motivated by the needs of the ILEX system for generating descriptions of musum artefacts (in particular, 20th Century jewellery) [Mellish et al 98]. We present results on examples semi-automatically generated from datastructures that exist within ILEX. Forming a set of facts about a piece of jewellery into a structure that yields a coherent text is a non-trivial problem. Rhetorical Structure Theory [Mann and Thompson 87] claims that a text is coherent just in case it can be analysed hierarchic..