James Bowen

A constraint programming language for Life-Cycle Engineering

Abstract Life-Cycle Engineering is a design methodology that takes into account the mutually constraining influences of product manufacturability, testability and maintainability as well as functionality. We are using non-directional constraint networks to model these mutually constraining influences in order to enable product designers to design more successful products without sacrificing functionality. To do this, we have developed Leo, a constraint programming language whose features have been specifically chosen to support Life-Cycle Engineering. In this paper, we introduce Leo and show its operation in the domain of printed wiring board design.

Constraint-based software for concurrent engineering

The Galileo3 programming language for developing product life-cycle design advice software is described. Galileo3s various application-oriented features, the algorithm on which the runtime system is based, and its underlying computational theory are discussed.<<ETX>>

Frames, quantification, perspectives, and negotiation in constraint networks for life-cycle engineering

Abstract In building design advisors for life-cycle engineering, it is necessary to model such entities as the artifact being designed, the components from which it is configured, and the life cycle environment in which it must be manufactured, tested and deployed. It is also necessary to enforce the mutually constraining influences that exist between the artifact, its components and the life-cycle environment. Furthermore, it is necessary to support the multiple perspectives on life-cycle design that are taken by members of the various engineering disciplines involved. We report on Galileo3, a programming language which provides frames for modeling entities; provides non-directional constraint networks for enforcing required relationships between these entities; enables the networks to be divided into different fields of view to reflect the perspectives of various engineering disciplines; and supports system-mediated negotiation between users of different perspectives in the event of incompatible decisions by these users. Features of the language are illustrated with an example program taken from the area of printed wiring board design.

Fuzzy semantics and fuzzy constraint networks

After reviewing the notion of crisp constraint networks and their relationship to semantics in classical logic, the authors define fuzzy constraint networks and their relationship to fuzzy logic. Then they introduce Khayyam, a fuzzy constrained-based programming language which implements much of Zadehs PRUF formalism. In Khayyam, any sentence in the first-order fuzzy predicate calculus is a well-formed constrained statement. Finally, using Khayyam to address an equipment selection application, the expressive power of constraint-based languages is illustrated.<<ETX>>

Artificial intelligence constraint nets applied to design for economic manufacture and assembly

Abstract Design decisions are reported to account for a significant portion of product manufacturing costs. Consequently, design for economic manufacture is an important area. This paper describes the background to the problem and the artificial intelligence (AI) approaches to design for economic manufacture that have been proposed. The use of AI approach of constraint nets for design for economic manufacture is then discussed. The use of constraint nets is illustrated by a descriptive overview of computer-aided design for economic manufacture and assembly (CADEMA). CADEMA is a research system which aids the designer in producing designs that satisfy both functional and manufacturing requirements.

Mixed quantitative/qualitative method for evaluating compromise solutions to conflicts in collaborative design

Conflicts are likely to arise among participants in a collaborative design process as the inevitable outgrowth of the differing perspectives and viewpoints involved. The opportunities for conflict are magnified if many perspectives are brought to bear on a common artifact early in the design process, as in concurrent engineering or integrated engineering. Design advice tools can assist in the process of resolving these conflicts by making critiques and suggestions conveniently available to design participants, and by offering a fair means of evaluating and comparing suggested alternatives for compromise solution. In previous work we introduced a protocol based on notions of economic utility by which design advice systems can recognize conflict and mediate negotiation fairly. This protocol allowed design teams to express the desire to maximize or minimize the values of design parameters over totally ordered bounded domains of values, such as real numeric intervals. In this paper we extend this approach by allowing expressed preferences of design teams to be qualitative as well as quantitative, by allowing teams to express interest in parameters before they actually come into existence, and by relaxing many other of the earlier restrictions on the ways teams may express their preferences.

An artificial intelligence approach to loading workstation resources in a distributed job shop controller

Abstract Job shop control involves directing the flow of work through a manufacturing job shop. After reviewing the shop control problem and various approaches towards its solution which have been described in the literature, this paper presents a brief overview of a shop activity manager (SAM), a shop controller which has a distributed architecture and which is based on artificial intelligence (AI) techniques. Attention is then focused on one aspect of the system: the approach used to avoid, as far as possible, overloading any manufacturing resource in the shop with more work than it can handle.

FMUFL: a fuzzy multi-paradigm language

Abstract Humans use a wide variety of formalisms to express themselves. In the course of a single exposition, a domain expert may use several modes of expression to present his expertise to a knowledge engineer. This, combined with the fact that building expert systems requires an iterative programming approach, and with the fact that much human expertise is couched in lexically imprecise terms, means that the trend in languages for knowledge engineering will be towards fuzzy multiparadigm languages. This paper presents a language which is the first step in this direction. The main points made in the paper are: there is a distinction between declarative and imperative productions; the truth value of a fact asserted by an imperative production can be completely unrelated to the truth value of the condition part of the production; relative truth-values should not be the primary criterion when resolving conflicts between imperative productions.

Static Parallel Arc Consistency in Constraint Satisfaction

Constraint satisfaction problems (CSPs) are ubiquitous in artificial intelligence; versions arise in areas such as vision, design, Boolean satisfiability, cryptarithmetic, and database retrieval. Most researchers have solved CSPs on sequential computers; relatively few have addressed the use of parallel computers for these problems. Among those who have investigated parallel approaches, several authors have solved CSPs using parallel tree search algorithms, while others have pre-processed constraint networks using parallel consistency algorithms. No one, however, has measured the specific work performed by the individual processors using arc consistency techniques to pre-process a constraint network. In this paper we introduce two Static Parallel Arc Consistency algorithms (SPAC-1 and SPAC-2), which ensure arc consistency of a finite domain binary constraint network, and which are designed for any general-purpose parallel processing computer. Through simulation, we measure work performed by each processor and compare it with work performed by existing sequential and parallel algorithms. Results show that our parallel arc consistency algorithm can be used to pre-process a constraint network with good speedup and utilization.

Aspects of constraint processing

Abstract Terms such as ‘constraint satisfaction’ and ‘constraint propagation’ are often used interchangeably although, in fact, they refer to different, albeit closely related, concepts. We discuss this and related confusions that sometimes arise in discussions of constraint processing