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.
12738746
Software support for practical grammar development
Even though progress in theoretical linguistics does not necessarily rely on the construction of working programs, a large proportion of current research in syntactic theory is facilitated by suitable computational tools. However, when natural language processing applications seek to draw on the results from new developments in theories of grammar, not only the nature of the tools has to change, but they face the challenge of reconciling the seemingly contradictory requirements of notational perspicuity and efficiency of performance. In this paper, we present a comparison and an evaluation of a number of software systems for grammar development, and argue that they are inadequate as practical tools for building wide-coverage grammars. We discuss a number of factors characteristic of this task, demonstrate how they influence the design of a suitable software environment, and describe the implementation of a system which has supported efficient development of a large computational grammar of English.
9629533
The Automatic Acquisition of Verb Subcategorisations and Their Impact on the Performance of an HPSG Parser
We describe the automatic acquisition of a lexicon of verb subcategorisations from a domain-specific corpus, and an evaluation of the impact this lexicon has on the performance of a “deep”, HPSG parser of English. We conducted two experiments to determine whether the empirically extracted verb stems would enhance the lexical coverage of the grammar and to see whether the automatically extracted verb subcategorisations would result in enhanced parser coverage. In our experiments, the empirically extracted verbs enhance lexical coverage by 8.5%. The automatically extracted verb subcategorisations enhance the parse success rate by 15% in theoretical terms and by 4.5% in practice. This is a promising approach for improving the robustness of deep parsing.
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.
3131824
From RAGS to RICHES: Exploiting the Potential of a Flexible Generation Architecture
The RAGS proposals for generic specification of NLG systems includes a detailed account of data representation, but only an outline view of processing aspects. In this paper we introduce a modular processing architecture with a concrete implementation which aims to meet the RAGS goals of transparency and reusability. We illustrate the model with the RICHES system -- a generation system built from simple linguistically-motivated modules.
1954
Corpus Annotation for Parser Evaluation
We describe a recently developed corpus annotation scheme for evaluating parsers that avoids shortcomings of current methods. The scheme encodes grammatical relations between heads and dependents, and has been used to mark up a new publicdomain corpus of naturally occurring English text. We show how the corpus can be used to evaluate the accuracy of a robust parser, and relate the corpus to extant resources.
14983459
Fixed vs. Dynamic Sub-Transfer in Reinforcement Learning
We survey various task transfer methods in Qlearning and present a variation on fixed sub-transfer which we call dynamic sub-transfer. We discuss the benefits and drawbacks of dynamic sub-transfer as compared with the other transfer methods, and we describe qualitatively the situations where this method would be preferred over the fixed version of sub-transfer. We test this method against several other transfer methods in a simple three room grid world where portions of the source’s policy are relevant to the target task and other portions are not. In this situation we found that dynamic sub-transfer converged to the optimal solution, avoiding the suboptimality inherent in fixed sub-transfer, while also avoiding some of the convergence problems often experienced by fixed sub-transfer.
10894513
Block-Level Consistency of Replicated Files
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.
5584278
Reinforcement Learning Task Clustering
14110921
The reuse of uses in Smalltalk programming
Software reuse, a long-standing and refractory issue in software technology, has been specifically emphasized as an advantage of the object-oriented programming paradigm. We report an empirical study of expert Smalltalk programmers reusing user interface classes in small graphical applications. Our primary goal was to develop a qualitative characterization of expert reuse strategies that could be used to identify requirements for teaching and supporting reuse programming. A secondary interest was to demonstrate to these experts the Reuse View Matcher—a prototype reuse tool—and to collect some initial observations of this tool in use during reuse programming. We observed extensive “reuse of uses” in the programmers' work: they relied heavily on code in expample applications that provided an implicit specification for reuse of the target class. We called this implicit specification a “usage context.” The programmers searched for relevant usage contexts early. They repeatedly evaluated the contextualized information to develop solution plans, and they borrowed and adapted it when the sample context suited their immediate reuse goals. The process of code development was highly dynamic and incremental; analysis and implementation were tightly interleaved, frequently driven by testing and debugging. These results are considered in terms of the tradeoffs that inhere in the reuse of uses and the teaching and tool support that might improve the efficiency and accuracy of this approach to reuse.