45352
A Practical Approach to Multiple Default Inheritance for Unification-Based Lexicons
This paper describes a unification-based lexicon system for NLP applications that incorporates mechanisms for multiple default inheritance. Such systems are intractable in the general case---the approach adopted here places a number of restrictions on the inheritance hierarchy in order to remove some of the sources of complexity while retaining more desirable properties. Implications of the design choices are discussed, comparisons are drawn with related work in computational linguistics and AI, and illustrative examples from the lexicons of German and English are given.
5587138
Automatic Extraction of Subcategorization from Corpora
We describe a novel technique and implemented system for constructing a subcategorization dictionary from textual corpora. Each dictionary entry encodes the relative frequency of occurrence of a comprehensive set of subcategorization classes for English. An initial experiment, on a sample of 14 verbs which exhibit multiple complementation patterns, demonstrates that the technique achieves accuracy comparable to previous approaches, which are all limited to a highly restricted set of subcategorization classes. We also demonstrate that a subcategorization dictionary built with the system improves the accuracy of a parser by an appreciable amount1.
14652639
Ambiguity Packing in Constraint-based Parsing Practical Results
We describe a novel approach to 'packing' of local ambiguity in parsing with a wide-coverage HPSG grammar, and provide an empirical assessment of the interaction between various packing and parsing strategies. We present a linear-time, bidirectional subsumption test for typed feature structures and demonstrate that (a) subsumption- and equivalence-based packing is applicable to large HPSG grammars and (b) average parse complexity can be greatly reduced in bottom-up chart parsing with comprehensive HPSG implementations.
14287805
A Formalism and Environment for the Development of a Large Grammar of English
Natural language grammars with large coverage are typically the result of many person-years of effort, working with clumsy formalisms and sub-optimal software support for grammar development. This paper describes our approach to the task of writing a substantial grammar, as part of a collaboration to produce a general purpose morphological and syntactic analyser for English. The grammatical formalism we have developed for the task is a metagrammatical notation which is a more expressive and computationally tractable variant of Generalized Phrase Structure Grammar. We have also implemented a software system which provides a highly integrated and very powerful set of tools for developing and managing a large grammar based on this notation. The system provides a grammarian with an environment which we have found to be essential for rapid but successful production of a substantial grammar.
16737045
Domain-Specific Sense Distributions and Predominant Sense Acquisition
Distributions of the senses of words are often highly skewed. This fact is exploited by word sense disambiguation (WSD) systems which back off to the predominant sense of a word when contextual clues are not strong enough. The domain of a document has a strong influence on the sense distribution of words, but it is not feasible to produce large manually annotated corpora for every domain of interest. In this paper we describe the construction of three sense annotated corpora in different domains for a sample of English words. We apply an existing method for acquiring predominant sense information automatically from raw text, and for our sample demonstrate that (1) acquiring such information automatically from a mixed-domain corpus is more accurate than deriving it from SemCor, and (2) acquiring it automatically from text in the same domain as the target domain performs best by a large margin. We also show that for an all words WSD task this automatic method is best focussed on words that are salient to the domain, and on words with a different acquired predominant sense in that domain compared to that acquired from a balanced corpus.
1627677
High Precision Extraction of Grammatical Relations
A parsing system returning analyses in the form of sets of grammatical relations can obtain high precision if it hypothesises a particular grammatical relation only when it is certain that the relation is correct. We operationalise this technique -in a statistical parser using a manually-developed wide-coverage grammar of English - by only returning relations that form part of all analyses licensed by the grammar. We observe an increase in precision from 75% to over 90% (at the cost of a reduction in recall) on a test corpus of naturally-occurring text.
11544923
Unparsing RDF/XML
It is difficult to serialize an RDF graph as a humanly readable RDF/XML document. This paper describes the approach taken in Jena 1.2, in which a design pattern of guarded procedures invoked using top down recursive descent is used. Each procedure corresponds to a grammar rule; the guard makes the choice about the applicability of the production. This approach is seen to correspond closely to the design of an LL(k) parser, and a theoretical justification of this correspondence is found in universal algebra.
1970300
Acting out the future: a process for envisionment
It is difficult to design innovative information and communication technologies to meet needs that will emerge from future interactions between users, technologies and their situations of use. We have been using scenarios that are acted out as a way of envisioning the future. This paper describes some of the core dilemmas of innovative design. It draws on our existing work as well as ideas from a range of disciplines to present a ‘light’ but useful envisionment process that may be applied to commercial design problems.
148806746
Human-computer interaction: psychology as a science of design.
39105600
Estimating the Reliability of Regeneration-Based Replica Control Protocols
The accessibility of vital information can be enhanced by replicating the data on several sites and employing a consistency control protocol to manage the replicas. The reliability of a replicated data object depends on maintaining a viable set of current replicas. When storage is limited, it may not be feasible to simply replicate a data object at enough sites to achieve the desired level of reliability. Regeneration approximates the reliability provided by additional replicas for a modest increase in storage costs, and is applicable whenever a new replica of a data object can be created faster than a system failure can be repaired. Regeneration enhances reliability by creating new replicas on other sites in response to site failures. Several strategies for replica maintenance are considered, and the benefits of each are analyzed using simulation and both algebraic and numeric solutions to systems of differential equations. >
58199435
Usability engineering - scenario-based development of human-computer interaction
Usability Engineering: Scenario-Based Development of Human-Computer Interaction is a radical departure from traditional books that emphasize theory and address experts. This book focuses on the realities of product development, showing how user interaction scenarios can make usability practices an integral part of interactive system development. As you'll learn, usability engineering is not the application of inflexible rules; it's a process of analysis, prototyping, and problem solving in which you evaluate tradeoffs, make reasoned decisions, and maximize the overall value of your product.