Extracting Noun Phrases from Large-Scale Texts: A Hybrid Approach and Its Automatic Evaluation

To acquire noun phrases from running texts is useful for many applications, such as word grouping,terminology indexing, etc. The reported literatures adopt pure probabilistic approach, or pure rule-based noun phrases grammar to tackle this problem. In this paper, we apply a probabilistic chunker to deciding the implicit boundaries of constituents and utilize the linguistic knowledge to extract the noun phrases by a finite state mechanism. The test texts are SUSANNE Corpus and the results are evaluated by comparing the parse field of SUSANNE Corpus automatically. The results of this preliminary experiment are encouraging.Comment: 8 pages, Postscript file, Unix compressed, uuencode

Corpus linguistics and language learning: bootstrapping linguistic knowledge and resources from text

This submission for the award of the degree of PhD by published work must: “make a contribution to knowledge in a coherent and related subject area; demonstrate originality and independent critical ability; satisfy the examiners that it is of sufficient merit to qualify for the award of the degree of PhD.” It includes a selection of my work as a Lecturer (and later, Senior Lecturer) at Leeds University, from 1984 to the present. The overall theme of my research has been bootstrapping linguistic knowledge and resources from text. A persistent strand of interest has been unsupervised and semi-supervised machine learning of linguistic knowledge from textual sources; the attraction of this approach is that I could start with English, but go on to apply analogous techniques to other languages, in particular Arabic. This theme covers a broad range of research over more than 20 years at Leeds University which I have divided into 8 sub-topics: A: Constituent-Likelihood statistical modelling of English grammar; B: Machine Learning of grammatical patterns from a corpus; C: Detecting grammatical errors in English text; D: Evaluation of English grammatical annotation models; E: Machine Learning of semantic language models; F: Applications in English language teaching; G: Arabic corpus linguistics; H: Applications in Computing teaching and research. The first section builds on my early years as a lecturer at Leeds University, when my research was essentially a progression from my previous work at Lancaster University on the LOB Corpus Part-of-Speech Tagging project (which resulted in the Tagged LOB Corpus, a resource for Corpus Linguistics research still in use today); I investigated a range of ideas for extending and/or applying techniques related to Part-of-Speech tagging in Corpus Linguistics. The second section covers a range of co-authored papers representing grant-funded research projects in Corpus Linguistics; in this mode of research, I had to come up with the original ideas and guide the project, but much of the detailed implementation was down to research assistant staff. Another highly productive mode of research has been supervision of research students, leading to further jointly-authored research papers. I helped formulate the research plans, and guided and advised the students; as with research-grant projects, the detailed implementation of the research has been down to the research students. The third section includes a few of the most significant of these jointly-authored Corpus Linguistics research papers. A “standard” PhD generally includes a survey of the field to put the work in context; so as a fourth section, I include some survey papers aimed at introducing new developments in corpus linguistics to a wider audience

Integrating deep and shallow natural language processing components : representations and hybrid architectures

We describe basic concepts and software architectures for the integration of shallow and deep (linguistics-based, semantics-oriented) natural language processing (NLP) components. The main goal of this novel, hybrid integration paradigm is improving robustness of deep processing. After an introduction to constraint-based natural language parsing, we give an overview of typical shallow processing tasks. We introduce XML standoff markup as an additional abstraction layer that eases integration of NLP components, and propose the use of XSLT as a standardized and efficient transformation language for online NLP integration. In the main part of the thesis, we describe our contributions to three hybrid architecture frameworks that make use of these fundamentals. SProUT is a shallow system that uses elements of deep constraint-based processing, namely type hierarchy and typed feature structures. WHITEBOARD is the first hybrid architecture to integrate not only part-of-speech tagging, but also named entity recognition and topological parsing, with deep parsing. Finally, we present Heart of Gold, a middleware architecture that generalizes WHITEBOARD into various dimensions such as configurability, multilinguality and flexible processing strategies. We describe various applications that have been implemented using the hybrid frameworks such as structured named entity recognition, information extraction, creative document authoring support, deep question analysis, as well as evaluations. In WHITEBOARD, e.g., it could be shown that shallow pre-processing increases both coverage and efficiency of deep parsing by a factor of more than two. Heart of Gold not only forms the basis for applications that utilize semanticsoriented natural language analysis, but also constitutes a complex research instrument for experimenting with novel processing strategies combining deep and shallow methods, and eases replication and comparability of results.Diese Arbeit beschreibt Grundlagen und Software-Architekturen für die Integration von flachen mit tiefen (linguistikbasierten und semantikorientierten) Verarbeitungskomponenten für natürliche Sprache. Das Hauptziel dieses neuartigen, hybriden Integrationparadigmas ist die Verbesserung der Robustheit der tiefen Verarbeitung. Nach einer Einführung in constraintbasierte Analyse natürlicher Sprache geben wir einen Überblick über typische Aufgaben flacher Sprachverarbeitungskomponenten. Wir führen XML Standoff-Markup als zusätzliche Abstraktionsebene ein, mit deren Hilfe sich Sprachverarbeitungskomponenten einfacher integrieren lassen. Ferner schlagen wir XSLT als standardisierte und effiziente Transformationssprache für die Online-Integration vor. Im Hauptteil der Arbeit stellen wir unsere Beiträge zu drei hybriden Architekturen vor, welche auf den beschriebenen Grundlagen aufbauen. SProUT ist ein flaches System, das Elemente tiefer Verarbeitung wie Typhierarchie und getypte Merkmalsstrukturen nutzt. WHITEBOARD ist das erste System, welches nicht nur Part-of-speech-Tagging, sondern auch Eigennamenerkennung und flaches topologisches Parsing mit tiefer Verarbeitung kombiniert. Schließlich wird Heart of Gold vorgestellt, eine Middleware-Architektur, welche WHITEBOARD hinsichtlich verschiedener Dimensionen wie Konfigurierbarkeit, Mehrsprachigkeit und Unterstützung flexibler Verarbeitungsstrategien generalisiert. Wir beschreiben verschiedene, mit Hilfe der hybriden Architekturen implementierte Anwendungen wie strukturierte Eigennamenerkennung, Informationsextraktion, Kreativitätsunterstützung bei der Dokumenterstellung, tiefe Frageanalyse, sowie Evaluationen. So konnte z.B. in WHITEBOARD gezeigt werden, dass durch flache Vorverarbeitung sowohl Abdeckung als auch Effizienz des tiefen Parsers mehr als verdoppelt werden. Heart of Gold bildet nicht nur Grundlage für semantikorientierte Sprachanwendungen, sondern stellt auch eine wissenschaftliche Experimentierplattform für weitere, neuartige Kombinationsstrategien dar, welche zudem die Replizierbarkeit und Vergleichbarkeit von Ergebnissen erleichtert

Proceedings of ROCLING-93, pp. 99-117 A PROBABILISTIC CHUNKER

This paper proposes a probabilistic partial parser, which we call chunker. The chunker partitions the input sentence into segments. This idea is motivated by the fact that when we read a sentence, we read it chunk by chunk. We train the chunker from Susanne Corpus, which is a modified but shrunk version of Brown Corpus, underlying bi-gram language model. The experiment is evaluated by outside test and inside test. The preliminary results show the chunker has more than 98 % chunk correct rate and 94% sentence correct rate in outside test, and 99 % chunk correct rate and 97 % sentence correct rate in inside test. The simple but effective chunker design has shown to be promising and can be extended to complete parsing and many applications. 1

Extracting Noun Phrases from Large-Scale Texts: A Hybrid Approach and Its Automatic Evaluation

In Proceedings of the 32nd Annual Meeting of the Association for Computational Linguistics (pp. 234-241)To acquire noun phrases from running texts is useful for many applications, such as word grouping, terminology indexing, etc. The reported literatures adopt pure probabilistic approach, or pure rule-based noun phrases grammar to tackle this problem. In this paper, we apply a probabilistic chunker to deciding the implicit boundaries of constituents and utilize the linguistic knowledge to extract the noun phrases by a finite state mechanism. The test texts are SUSANNE Corpus and the results are evaluated by comparing the parse field of SUSANNE Corpus automatically. The results of this preliminary experiment are encouraging