41 research outputs found
Detailed Design and Partial Implementation of a Pre-processor for Prolog Programs with Embedded C Statements
Computer Scienc
Investigation of design and execution alternatives for the committed choice non-deterministic logic languages
The general area of developing, applying and studying new and parallel models
of computation is motivated by a need to overcome the limits of current Von
Neumann based architectures. A key area of research in understanding how new
technology can be applied to Al problem solving is through using logic languages.
Logic programming languages provide a procedural interpretation for sentences of
first order logic, mainly using a class of sentence called Horn clauses. Horn clauses
are open to a wide variety of parallel evaluation models, giving possible speed-ups
and alternative parallel models of execution.
The research in this thesis is concerned with investigating one class of parallel
logic language known as Committed Choice Non-Deterministic languages. The investigation
considers the inherent parallel behaviour of Al programs implemented
in the CCND languages and the effect of various alternatives open to language
implementors and designers. This is achieved by considering how various Al programming
techniques map to alternative language designs and the behaviour of
these Al programs on alternative implementations of these languages.
The aim of this work is to investigate how Al programming techniques are
affected (qualitatively and quantitatively) by particular language features. The
qualitative evaluation is a consideration of how Al programs can be mapped to
the various CCND languages. The applications considered are general search
algorithms (which focuses on the committed choice nature of the languages); chart
parsing (which focuses on the differences between safe and unsafe languages);
and meta-level inference (which focuses on the difference between deep and flat
languages). The quantitative evaluation considers the inherent parallel behaviour
of the resulting programs and the effect of possible implementation alternatives
on this inherent behaviour. To carry out this quantitative evaluation we have
implemented a system which improves on the current interpreter based evaluation
systems. The new system has an improved model of execution and allows severa
SAGA: A project to automate the management of software production systems
The Software Automation, Generation and Administration (SAGA) project is investigating the design and construction of practical software engineering environments for developing and maintaining aerospace systems and applications software. The research includes the practical organization of the software lifecycle, configuration management, software requirements specifications, executable specifications, design methodologies, programming, verification, validation and testing, version control, maintenance, the reuse of software, software libraries, documentation, and automated management
Classification-based phrase structure grammar: an extended revised version of HPSG
This thesis is concerned with a presentation of Classification -based Phrase Structure
Grammar (or cPSG), a grammatical theory that has grown out of extensive revisions
of, and extensions to, HPSG. The fundamental difference between this theory and HPSG
concerns the central role that classification plays in the grammar: the grammar classifies
strings, according to their feature structure descriptions, as being of various types.
Apart from the role of classification, the theory bears a close resemblance to HPSG,
though it is by no means a direct translation, including numerous revisions and extensions.
A central goal in the development of the theory has been its computational
implementation, which is included in the thesis.The presentation may be divided into four parts. In the first, chapters 1 and 2, we
present the grammatical formalism within which the theory is stated. This consists of a
development of the notion of a classificatory system (chapter 1), and the incorporation
of hierarchality into that notion (chapter 2).The second part concerns syntactic issues. Chapter 3 revises the HPSG treatment of
specifiers, complements and adjuncts, incorporating ideas that specifiers and complements
should be distinguished and presenting a treatment of adjuncts whereby the
head is selected for by the adjunct. Chapter 4 presents several options for an account of
unbounded dependencies. The accounts are based loosely on that of GPSG, and a reconstruction
of GPSG's Foot Feature Principle is presented which does not involve a notion
of default. Chapter 5 discusses coordination, employing an extension of Rounds- Kasper
logic to allow a treatment of cross -categorial coordination.In the third part, chapters 6, 7 and 8, we turn to semantic issues. We begin (Chapter 6)
with a discussion of Situation Theory, the background semantic theory, attempting to
establish a precise and coherent version of the theory within which to work. Chapter 7
presents the bulk of the treatment of semantics, and can be seen as an extensive revision
of the HPSG treatment of semantics. The aim is to provide a semantic treatment which
is faithful to the version of Situation Theory presented in Chapter 6. Chapter 8 deals
with quantification, discussing the nature of quantification in Situation Theory before
presenting a treatment of quantification in CPSG. Some residual questions about the
semantics of coordinated noun phrases are also addressed in this chapter.The final part, Chapter 9, concerns the actual computational implementation of the
theory. A parsing algorithm based on hierarchical classification is presented, along with
four strategies that might be adopted given that algorithm. Also discussed are some
implementation details. A concluding chapter summarises the arguments of the thesis
and outlines some avenues for future research