Logic Programming: Context, Character and Development

Logic programming has been attracting increasing interest in recent years. Its first realisation in the form of PROLOG demonstrated concretely that Kowalski's view of computation as controlled deduction could be implemented with tolerable efficiency, even on existing computer architectures. Since that time logic programming research has intensified. The majority of computing professionals have remained unaware of the developments, however, and for some the announcement that PROLOG had been selected as the core language for the Japanese 'Fifth Generation' project came as a total surprise. This thesis aims to describe the context, character and development of logic programming. It explains why a radical departure from existing software practices needs to be seriously discussed; it identifies the characteristic features of logic programming, and the practical realisation of these features in current logic programming systems; and it outlines the programming methodology which is proposed for logic programming. The problems and limitations of existing logic programming systems are described and some proposals for development are discussed. The thesis is in three parts. Part One traces the development of programming since the early days of computing. It shows how the problems of software complexity which were addressed by the 'structured programming' school have not been overcome: the software crisis remains severe and seems to require fundamental changes in software practice for its solution. Part Two describes the foundations of logic programming in the procedural interpretation of Horn clauses. Fundamental to logic programming is shown to be the separation of the logic of an algorithm from its control. At present, however, both the logic and the control aspects of logic programming present problems; the first in terms of the extent of the language which is used, and the second in terms of the control strategy which should be applied in order to produce solutions. These problems are described and various proposals, including some which have been incorporated into implemented systems, are described. Part Three discusses the software development methodology which is proposed for logic programming. Some of the experience of practical applications is related. Logic programming is considered in the aspects of its potential for parallel execution and in its relationship to functional programming, and some possible criticisms of the problem-solving potential of logic are described. The conclusion is that although logic programming inevitably has some problems which are yet to be solved, it seems to offer answers to several issues which are at the heart of the software crisis. The potential contribution of logic programming towards the development of software should be substantial

An application of formal semantics to student modelling : an investigation in the domain of teaching Prolog

This thesis reports on research undertaken in an exploration of the use of formal semantics for student modelling in intelligent tutoring systems. The domain chosen was that of tutoring programming languages and within that domain Prolog was selected to be the target language for this exploration. The problem considered is one of how to analyse students' errors at a level which allows diagnosis to be more flexible and meaningful than is possible with the 'mal-rules' and 'bugcatalogue' approach of existing systems. The ideas put forward by Robin Milner [1980] in his Calculus of Communicating Systems (CCS) form the basis of the formalism which is proposed as a solution to this problem. Based on the findings of an empirical investigation, novices' misconceptions of control flow in Prolog was defined as a suitable area in which to explore the application of this solution. A selection of Prolog programs used in that investigation was formally described in terms of CCS. These formal descriptions were used by a production rule system to generate a number of the incomplete or faulty models of Prolog execution which were identified in the first empirical study. In a second empirical study, a machine-analysis tool, designed to be part of a diagnostic tutoring module, used these models to diagnose students' misconceptions of Prolog control flow. This initial application of CCS to student modelling showed that the models of Prolog execution generated by the system could be used successfully to detect students' misunderstandings. Results from the research reported here indicate that the use of formal semantics to model programming languages has a useful contribution to make to the task of student modelling

A report on the commercial and educational applications of expert systems

Expert, or intelligent knowledge-based, systems have emerged as the main practical application of Artificial Intelligence research. This thesis reports on their history, development and increasing commercial application. An analysis of the tasks and domains of 785 systems is reported which indicated a level of task specificity. The technology is suggestive of significant educational relevance as it is closely linked with concepts of expertise, intelligence, knowledge and learning. These basic educational concepts are discussed. The thesis reports on a survey of the use of the NCC Expert System Starter Pack in Further and Higher Education. The relationship between other computer-based learning systems and expert systems are discussed and it is argued that the development of intelligent tutoring systems is a more complex operation than the educational application of expert systems. A wide spectrum of potential educational applications is indicated. It is suggested that placing pupils in the position of knowledge engineers provides an exciting curriculum application. It is further argued that the use of expert systems in a commercial training role promises to be a major future development. Other educational applications are considered and the wider social implications associated with the use of expert systems are summarised

Legal knowledge engineering: Computing, logic and law

The general problem approached in this thesis is that of building computer based legal advisory programs (otherwise known as expert systems or Intelligent Knowledge Based Systems). Such computer systems should be able to provide an individual with advice about either the general legal area being investigated, or advice about how the individual should proceed in a given case. In part the thesis describes a program (the ELl program) which attempts to confront some of the problems inherent in the building of these systems. The ELl system is seen as an experimental program (currently handling welfare rights legislation) and development vehicle. It is not presented as a final commercially implementable program. We present a detailed criticism of the type of legal knowledge contained within the system. The second, though in part intertwined, major subject of the thesis describes the jurisprudential aspects of the attempt to model the law by logic, a conjunction which is seen to be at the heart of the computer/law problem. We suggest that the conjunction offers very little to those who are interested in the real application of the real law, and that this is most forcefully seen when a working computer system models that conjunction. Our conclusion is that neither logic nor rule-based methods are sufficient for handling legal knowledge. The novelty and import of this thesis is not simply that it presents a negative conclusion; rather that it offers a sound theoretical and pragmatic framework for understanding why these methods are insufficient - the limits to the field are, in fact, defined

The design and formative evaluation of computer based qualitative modelling environments for schools

This research investigated how computers might enable young learners to build models so that they can express and explore their ideas and hence they can gain understanding of the subject matter as well as developing modelling abilities. A design for a qualitative modelling environment was produced, which incorporated a simple rule-based metaphor that could be presented as a diagram. The design was founded on empirical evidence of children modelling as well as theoretical grounds. This research originated in and contributed to the Modus Project, a joint venture between King's College London and the Advisory Unit for Microtechnology in Education, Hertfordshire County Council. A prototype of the software, Expert Builder, was implemented by software engineers from the Modus team. The initial stage of evaluation, based on a questionnaire survey and widespread trialling, established that the tool could be used in a wide range of educational contexts. A detailed study of children using the qualitative modelling environment was conducted in three primary schools involving 34 pupils, aged nine to 11. They used the modelling environment within the classroom in their normal curriculum work over one school year on a variety of topics assisted by their class teacher. The modelling environment enabled cooperative groupwork and supported pupils in consolidating and extending their knowledge. A formative evaluation was used to inform the design of a revised version of the software. In addition the experiences of children using the software were analysed. A framework was developed which characterised the stages in the modelling process. Teachers in the study were observed to demonstrate the earlier stages of the modelling process and then to set tasks for the children based on the later stages of building and testing the models. The evidence suggested that the abilities to model were context dependent so that pupils as young as nine years old could undertake the whole modelling process provided that they were working on subject matter with which they were familiar. The teachers made use of computer based modelling in order to develop and reinforce pupils' understanding of various aspects of the curriculum and therefore they chose modelling tasks for the children. However in one school the children were given the opportunity to design and build models of their own choice and they demonstrated that they were able to carry out all the stages in the modelling process. A taxonomy of computer based modelling is proposed which could be used to inform decisions about the design of the modelling curriculum and could provide a basis for researchers investigating the modelling process. This would be useful for further research into the intellectual and social activities of people learning to model and for teachers seeking to develop a framework for the modelling curriculum. The National Curriculum (Department of Education and Science and the Welsh Office, 1990) specifies that early steps in computer based modelling should involve exploring models developed by others and pupils are not required to build models themselves until level 7 which is expected to be reached by more able 14 year-olds. In this thesis it is argued that a modelling curriculum should provide early opportunities for pupils to undertake the modelling process by developing simple models on familiar subject matter as well as opportunities for exploring more complex models as evidence from research reported in this thesis suggests that younger pupils are able to build models. In this way pupils will be enabled to acquire modelling capability as well as developing their understanding of a range of topics through modelling. Progression in modelling capability would involve constructing models of more complex situations and using a wider range of modelling environments

Embodying conversational characteristics in a graphical user interface

In the history of Intelligent Tutoring Systems, SOPHIE (Brown, Burton, and Bell, 1974), now considered a classic, contained many important ideas and features. One of these was its natural language user interface. Today, the trend has moved away from natural language interfaces towards graphical ones although the argument in favour of natural language user interfaces, both from Human Computer Interaction and natural language researchers, still persist. Is this argument correct? This thesis explores this question by investigating how SOPHIE might be re-implemented with a graphical direct manipulation interface instead of a natural language one, with the goal of improving its standard of usability. It begins by analysing the features that seem to have been central to SOPHIE's usability. These, it argues, were not so much an ability to accept well formed complete English sentences, as an ability to accept and interpret correctly a wide range of abbreviated inputs. Two models of interaction, Circuit 1, a pilot, and Circuit II, a fairly full implementation of SOPHIE were implemented and tested. Both employ free-order syntax that allows users to specify the components of a full command in any order. The combination of deixis and free-order syntax supported allows completely general ellipsis which achieves, in extended interaction sequences, the same economy and naturalness that SOPHIE achieved through its use of anaphora and ellipsis. Whilst the free-order syntax. technique is little used at present in user interfaces, the results of observational studies conducted have shown that it saves users time and convenience. Thus, considering key linguistic features of a natural language user interface has shown how novel features can enhance the usability of direct manipulation interfaces. This thesis argues that user interfaces can be improved by employing structures found in natural language or at least conversation which can be constructed within direct manipulation interface styles. This approach was further expanded to support topic shifts between different circuit contexts. Circuit II, like SOPHIE, supports three different topics: normal circuit behaviour, a circuit with an unknown fault, and circuits with user-hypothesised faults. Drawing on Reichman's (1981) work, Circuit II uses natural language cue phrases of the type "by the way", re-implemented in the direct manipulation style, to facilitate shifts between topics in a smoother and more natural way than SOPHIE which , used clumsy explicit commands

Decision support for the management of essential hypertension

The thesis presents a decision support system targeted at the needs of health care professionals in primary care. The architecture of the new decision support system is based on a model of the management of a patient with essential hypertension, that itself is based on the observation of the interactions between medical practitioner and patient and the recognition and formalisation of the steps in that process. The need for a new decision support system is driven by two independent factors. Firstly rapid advances in medical knowledge have created enormous pressures on practitioners, who have a real need to maintain and update their medical knowledge. Secondly rapid advances in computer technology, particularly in the 1990s with the introduction of new design features into desk top computers has created opportunities for system designers to introduce a wide range of facilities into user interfaces, which in turn, provide medical practitioners with tools that are both useful and easy to use. In effect it is the combination of a medical need and user friendly technology that now enables an embedded decision support system to be demonstrated. The work that is reported in the thesis has three main features, which have been implemented into a prototype demonstrator: Firstly, a model of the management of a patient with essential hypertension is described which enables decision support to reflect the decision making needs of the clinician and to interface transparently with their normal working practice. Secondly, the system architecture which enables a range of decision support components to be embedded within the normal consultation environment is described. This approach has enabled convenience, ease of access and ease of use of decision support facilities, to be demonstrated. Thirdly, clinical guidelines have been utilised to form the foundation of the systems knowledge base. In using these guidelines it has been noted that they have been developed by several international teams of medical experts to guide doctors in their diagnosis and treatment of patients with essential hypertension. The thesis concludes with the results of the system evaluation. The evaluations have enabled the methods and techniques that have been used to design and develop the new system to be tested, and for the advice generated by the system to be compared with current medical opinions

Knowledge-based approaches to fault diagnosis. The development, implementation, evaluation and comparison of knowledge-based systems, incorporating deep and shallow knowledge, to aid in the diagnosis of faults in complex hydro-mechanical devices.

The use of knowledge-based systems to aid in the diagnosis of faults in physical devices has grown considerably since their introduction during the 1970s. The majority of the early knowledge-based systems incorporated shallow knowledge, which sought to define simple cause and effect relationships between a symptom and a fault, that could be encoded as a set of rules. Though such systems enjoyed much success, it was recognised that they suffered from a number of inherent limitations such as inflexibility, inadequate explanation, and difficulties of knowledge elicitation. Many of these limitations can be overcome by developing knowledge-based systems which contain deeper knowledge about the device being diagnosed. Such systems, now generally referred to as model-based systems, have shown much promise, but there has been little evidence to suggest that they have successfully made the transition from the research centre to the workplace. This thesis argues that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex devices, and that both deep and shallow knowledge have their part to play in this process. More specifically this thesis demonstrates how a wide-ranging knowledge-based system for quality assurance, based upon shallow knowledge, can be developed, and implemented. The resultant system, named DIPLOMA, not only diagnoses faults, but additionally provides advice and guidance on the assembly, disassembly, testing, inspection and repair of a highly complex hydro-mechanical device. Additionally it is shown that a highly innovative modelbased system, named MIDAS, can be used to contribute to the provision of diagnostic, explanatory and training facilities for the same hydro-mechanical device. The methods of designing, coding, implementing and evaluating both systems are explored in detail. The successful implementation and evaluation of the DIPLOMA and MIDAS systems has shown that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex hydro-mechanical devices, and that they make a beneficial contribution to the business performance of the host organisation. Furthermore, it has been demonstrated that the most effective and comprehensive knowledge-based approach to fault diagnosis is one which incorporates both deep and shallow knowledge, so that the distinctive advantages of each can be realised in a single application. Finally, the research has provided evidence that the model-based approach to diagnosis is highly flexible, and may, therefore, be an appropriate technique for a wide range of industrial applications.Science and Engineering Research Council, and Alvey Directorat

Impacts of Artificial Intelligence

This book, which is intended to serve as the first stage in an iterative process of detecting, predicting, and assessing the impacts of Artificial Intelligence opens with a short "one-hour course" in AI, which is intended to provide a nontechnical informative introduction to the material which follows. Next comes an overview chapter which is based on an extensive literature search, the position papers, and discussions. The next section of the book contains position papers whose richness and diversity illustrate the wealth of opinions and research directions that today fall under the umbrella term "AI research". The papers are followed by a select bibliography containing nearly 700 books, articles, and research memoranda on AI-related topics, together with a thesaurus and KWIC index to facilitate the retrieval of information. The book closes with and index and two appendices, one listing the names and addresses of the contributing scientists and the other giving details of the AI curriculum at the University of Vienna