Hammond, P., J.C. Davenport and F.J. Fitzpatrick, Logic-based integrity constraints and the design of dental prostheses, Artificial Intelligence in Medicine 5 (1993) 431-446 This paper describes the ongoing development of a design assistant, RaPiD, for use in prosthetic dentistry. RaPiD integrates computer-aided design, knowledge-based systems and databases, employing a logicbased representation as the unifying medium. The user's manipulation of icons representing the developing design is interpreted as a set of transactions on a logic database of design components. The rules of design expertise are represented as constraints in first order predicate logic and design alterations are subject to the checking of the constraints. When design rules are contravened as the result of some proposed alteration, a suitable critique is presented to the user. RaPiD is being developed for use in both dental education and practice. Keywords Computer-aided design, critiquing, knowledge-based...

This paper describes an investigation into the proof facilities within the BToolkit based on a study of the specification and refinement of low level code in the control systems domain. We describe the problems we encountered and some means by which these problems can be tackled within the existing framework. We conclude with some more general guidelines by which the proof facilities could be enhanced to improve the effectiveness of the provers for industrial scale verification of formal developments. 1 Introduction Formal development has been advocated for use in industrial control systems design, especially for safety-critical applications. Formal proof is an important source of confidence in such developments. However, it is perceived as an expensive and highly specialised task. If the full benefit of the formal approach is to be attained, the development of viable methods to aid the production of proofs is essential. In a reference to programming, Kowalski[13] coined a fam...

We present a prescriptive type system with parametric polymorphism and subtyping for constraint logic programs. The aim of this type system is to detect programming errors statically. It introduces a type discipline for constraint logic programs and modules, while maintaining the capabilities of performing the usual coercions between constraint domains, and of typing meta-programming predicates, thanks to the exibility of subtyping. The property of subject reduction expresses the consistency of a prescriptive type system w.r.t. the execution model: if a program is \well-typed", then all derivations starting from a \well-typed" goal are again \well-typed". That property is proved w.r.t. the abstract execution model of constraint programming which proceeds by accumulation of constraints only, and w.r.t. an enriched execution model with type constraints for substitutions. We describe our implementation of the system for type checking and type inference. We report our experimental results on type checking ISO-Prolog, the (constraint) libraries of Sicstus Prolog and other Prolog programs.

le to writing programs that embody the relevant problem knowledge written in a form that is close to the one in which it is expressed by human experts. However, the knowledge pieces are frequently related to each other according to various properties: some of them can be more general than some others, some can define ways how to evaluate, select, or manipulate other ones, etc. It would be very useful to keep such relations represented in the knowledge base. Less general knowledge pieces could inherit some of the properties of the more general ones without having to re-represent them. Knowledge pieces that manipulate other pieces could be grouped to form an explicit meta-level of knowledge representation. The desire to have in a logic programming language such as Prolog means a The work reported here was partially supported by Slovak Science Grant Agency, grant No. 95/5195/605. 1 for dividing a software system into smaller relatively separated and ind

This paper discusses and illustrates the application of Empirical Modelling (EM), as developed by the author and his collaborators', to computer programming. The discussion centres on the perspective EM gives on procedural and experiential vs. declarative and logical approaches to knowledge representation. The illustration focuses on demonstrating the potential for pedagogical use of EM in teaching algorithms. It is based on a family of practical models that have been developed to teach the principles of heapsort.

The need to make default assumptions is frequently encountered in reasoning'about incompletely specified worlds. Inferences sanctioned by default are best viewed as beliefs which may well be modified or rejected by subsequent observations. It is this property which leads to the non.monotonJcity of any logic of defaults. In this paper we propose a logic for default reasoning. We then specialize our treatment to a very large class of commonly occurring defaults. For this class we develop a complete proof theory and show how to interface it with a top down resolution theorem prover. Finally, we provide criteria under which the revision of derived beliefs must be effected. The gods did not reveal, from the beginning, All things to us, but in the course of time Through seeking we may learn and know things better. But as for certain truth, no man has known it, Nor shall he know it, neither of the gods Nor yet of all the things of which I speak. For even if by chance he were to utter The final truth, he would himself not know it: For all is but a woven web of guesses. Xenophanes 1.