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Showing papers in "Expert Systems in 1991"


Journal Article
TL;DR: An interval-based temporal logic is introduced, together with a computationally effective reasoning algorithm based on constraint propagation, which is notable in offering a delicate balance between space and time.
Abstract: An interval-based temporal logic is introduced, together with a computationally effective reasoning algorithm based on constraint propagation. This system is notable in offering a delicate balance between

7,466 citations


Book ChapterDOI
TL;DR: The Rete Match Algorithm is an efficient method for companng a large collection of patterns to a largeCollection of objects that finds all the objects that match each pattern.
Abstract: The Rete Match Algorithm is an efficient method for companng a large collection of patterns to a large collection of objects. It finds all the objects that match each pattern The algorithm was developed for use in production system interpreters, and it has been used for systems containing from a few hundred to more than a thousand patterns and objects. This article presents the algorithm in detail It explains the basic concepts of the algorithm, it describes pattern and object representations that are appropriate for the algorithm, and it describes the operations performed by the pattern matcher.

1,555 citations


Journal Article
TL;DR: A formalism is presented for representing commonsense knowledge using the notion of process and it is shown how this knowledge can be used to achieve particular goals or to form intentions regarding their achievement.
Abstract: Much of commonsense knowledge about the real world is in the form of procedures or sequences of actions for achieving particular goals. In this paper, a formalism is presented for representing such knowledge using the notion of process. A declarative semantics for the representation is given, which allows a user to state facts about the effects of doing things in the problem domain of interest. An operational semantics is also provided, which shows how this knowledge can be used to achieve particular goals or to form intentions regarding their achievement. Given both semantics, our formalism additionally serves as an executable specification language suitable for constructing complex systems. A system based on this formalism is described, and examples involving control of an autonomous robot and fault diagnosis for NASA's space shuttle are provided.

335 citations



Journal ArticleDOI
TL;DR: A depth·first iterative·deepening algorithm is shown to be asymptotically optimal along all three dimmsions for exponential tree searches and is the only known algorithm that is capable of finding optimal solUtions to randomly generated instances of the Fif/un Puzzle within practical resource.
Abstract: Richard E. Korf** Department of Computer Science, Columbia University. New York, NY 10027, U.S.A. 97 The complailits of various search algorithms are consuured in ~rms of time. space. and cost of solwion path. It is known that breadth·first search requires tOO much space and depth·first Starch can UM too much time and d~n't always find a cheapest path. A depth·first iterative·deepening algorithm is shown to be asymptotically optimal along all three dimmsions for exponential tree searches. The algorithm has been used succt$Sfully in chess programs, has bun effectively combined with bi-directional search. and has been applied to best·first heuristic search as well. This heuristic depth·first iterative· deePening algorithm is the only known algorithm that is capable of finding optimal solUtions to randomly generated instances of the Fif/un Puzzle within practical resource

94 citations


Journal Article

44 citations


Journal ArticleDOI
TL;DR: This paper outlines some of the issues involved in evaluating expert systems and cites almost 200 significant papers on the topic and aims to help both new and established researchers become acquainted with the literature of an important and growing field.
Abstract: The rapid growth in the use of expert systems has led to widespread interest in techniques for their evaluation, which includes verification and validation. Evaluation techniques in the software engineering community are well established but there are different opinions about the effectiveness of transferring software engineering methodologies to expert systems. This paper outlines some of the issues involved in evaluating expert systems and cites almost 200 significant papers on the topic. We present it with the expectation that it will help both new and established researchers become acquainted with the literature of an important and growing field.

42 citations


Journal Article
TL;DR: A nalogies and analogical thinking are aspects of problem solving that may be found in a variety of domains and can be used by both novices and experts.

38 citations


Journal Article
TL;DR: In this paper, the authors describe an implemented system supporting the maintenance of evolving symbolic models and the spreadsheet-like algebraic models based on them, which can be modified in response to changes in the task environment, and appropriate changes induced in the algebraic model to reflect changes in a symbolic model.
Abstract: The authors describe an implemented system supporting the maintenance of evolving symbolic models and the spreadsheet-like algebraic models based on them. The system's primitives are knowledge fragments that are instantiated into symbolic models; these fragments can be modified in response to changes in the task environment, and appropriate changes induced in the algebraic model to reflect changes in the symbolic model. They analyze model features for problem-solving in domains with three levels of structuredness: highly formalized problems. The authors define data structures used for representing choice sets and constraints and describe the system's procedural knowledge component, which allows knowledge represented in the structures to be used in an integrated way. >

26 citations


Journal ArticleDOI
TL;DR: An intelligent knowledge-based object-oriented process planning (IKOOPP) system for the manufacture of progressive die plates is described, which allows process planning information to be automatically deduced.
Abstract: This article describes an intelligent knowledge-based object-oriented process planning (IKOOPP) system for the manufacture of progressive die plates. A die assembly is designed using a variety of standardised components based on a computer-aided design (CAD) system. A feature recognition module extracts all the pertinent geometrical properties and functional attributes of each machining feature from the CAD representation models. These properties and attributes are converted into an object-oriented representation. Knowledge of the functions of the machining feature allows process planning information to be automatically deduced. Specialised tool engineering knowledge are formulated as production rules or procedures to establish the required set of cutting tools, together with the machining allowances and sequence of operations.

23 citations


Journal Article
TL;DR: In this paper, an interactive classifier uses the contents of the existing knowledge base and knowledge about its representation to help the maintainer describe new knowledge base objects and add them to the knowledge base.
Abstract: The practical application of knowledge-based systems, such as in expert systems, often requires the maintenance of large amounts of declarative knowledge. As a knowledge base (KB) grows in size and complexity, it becomes more difficult to maintain and extend. Even someone who is familiar with the knowledge domain, how it is represented in the KB, and the actual contents of the current KB may have severe difficulties in updating it. Even if the difficulties can be tolerated, there is a very real danger that inconsistencies and errors may be introduced into the KB through the modification. This paper describes an approach to this problem based on a tool called an interactive classifier. An interactive classifier uses the contents of the existing KB and knowledge about its representation to help the maintainer describe new KB objects. The interactive classifier will identify the appropriate taxonomic location for the newly described object and add it to the KB. The new object is allowed to be a generalization of existing KB objects, enabling the system to learn more about existing objects.

Journal Article
TL;DR: In this article, the authors describe the automatic design of custom integrated circuits from higher level specifications, including the problem domain and solution approach, higher level synthesis, module to layout automation systems, typically called silicon compiliers, and expert systems which control the design process.
Abstract: This paper describes the automatic design of custom integrated circuits from higher level specifications. The paper covers four topic areas: the problem domain and solution approach, higher level synthesis, module to layout automation systems, typically called silicon compiliers, and expert systems which control the design process. In the first three sections, several features of the VLSI problem domain which complicate automation are listed. The VLSI design process is diagrammed and the individual steps described. The term "silicon compilation" is defined to cover the entire process, and definitions for various subcategories of silicon compilers are given. The next Section describes both algorithmic and knowledge-based techniques Which perform higher level synthesis, including area estimation and module binding concurrent with synthesis. Research at Bell Labs, USC, CMU, and in Canada is described, along with other projects. The fifth section discusses the three categories of silicon compilers: commercially available systems, experimental compilers being developed by industry, and artificial intelligence approaches from university research. A survey of several systems is provided. The last section focuses on two systems developed at CMU and USC which plan or control design activities, Ulysses and DPE. Both systems allow the integration of various design automation tools and determine the proper tool invocation to automatically create a design. ADAM takes an autonomous approach, while ULYSSES follows user-defined scripts.

Journal ArticleDOI
TL;DR: A descriptive framework is presented which allows the depiction of essential features of a methodology and is intended to simplify the comparative study of KBSs that a knowledge engineer might be involved in.
Abstract: Instigating the selection of a methodological approach for the development of a knowledge-based system (KBS) should not be trivialised. This paper sets out to enlighten the reader about the needs and difficulties in comparing methodologies. In doing so, a descriptive framework is presented which allows the depiction of essential features of a methodology. This is intended to simplify the comparative study of KBSs that a knowledge engineer might be involved in.

Journal ArticleDOI
Franz Barachini1
TL;DR: A transputer-based architecture is developed which serves as a testbed for a new parallel matching algorithm and the execution speeds of various expert systems based on PAMELA are presented.
Abstract: This paper describes the results of a five-year research program on production systems carried out in Vienna by a large engineering group at the Alcatel-Elin research laboratory. In the course of our investigations, a real-time expert system shell, PAMELA, was developed. We describe features of PAMELA and discuss ways in which the matching algorithm can be speeded up. It was found that the single processor version is one of the most efficient forward chainers available worldwide. Since single processor enhancements have been widely explored, we concentrated our efforts on multiple processor architectures to provide further performance gain. Efficient exploitation of parallelism in production systems requires suitable algorithms for load-balancing, without simultaneously increasing organisational or communication overheads. With this in mind, we developed a transputer-based architecture which serves as a testbedfor our new parallel matching algorithm. The execution speeds of various expert systems based on PAMELA are presented.


Journal ArticleDOI
TL;DR: The TRISTAR expert system is a PC-based consultancy tool designed to help bridge the gap between academic plant ecology and practical vegetation management, and predicts the composition of a new steady-state vegetation in terms of plant-strategic types.
Abstract: The TRISTAR expert system (TRIangular STrAtegic Rules for British herbaceous vegetation) is a PC-based consultancy tool designed to help bridge the gap between academic plant ecology and practical vegetation management. It is a ‘what if facility, for use by students, naturalists, conservationists, planners, administrators; indeed anyone with an interest in environmental science and management, conservation or reconstruction of herbaceous vegetation. The system is written in Leonardo 3 (Creative Logic Limited, Uxbridge, UK). Release I of TRISTAR deals with the fundamental environmental and management processes which control the composition of British herbaceous vegetation. The system takes a specification of initial steady-state vegetation, asks the user to specify an altered environmental and/or management scenario, and predicts the composition of a new steady-state vegetation in terms of plant-strategic types. The high-level approach through plant strategies makes it possible to construct a very robust rulebase despite a lack of hard information in many areas of understanding.

Journal Article
TL;DR: The authors focus on methodological issues that establish knowledge engineering as an alternative to structured analysis and design, concentrating on the acquisition of strategic knowledge as an implementation structure determinant.
Abstract: The authors focus on methodological issues that establish knowledge engineering as an alternative to structured analysis and design, concentrating on the acquisition of strategic knowledge as an implementation structure determinant. They analyze benefits derived from applying expert systems in cellular telecommunications systems, discuss related artificial intelligence work, define structural characteristics of knowledge-based systems, examine a verbal problem-solving protocol from an expert, describe a prototypical knowledge-based program, and review methods and results. They discuss the role of deep knowledge in maintenance tasks, present the resulting system design, and examine the relevant development methodology. >

Journal ArticleDOI
TL;DR: The main goal of this shell is to generate a community of cooperative knowledge-based systems and to develop several special reasoning techniques which can be used under a distributed and cooperative paradigm.
Abstract: This paper describes a shell for cooperating expert systems that has been developed at the University of Porto. The main goal of this shell is two-fold: to generate a community of cooperative knowledge-based systems and to develop several special reasoning techniques which can be used under a distributed and cooperative paradigm. UPShell is able to convert a set of generated intelligent systems (ISs) into a community of cooperative ISs. In this first version it is already possible to generate different intelligent systems which are able to run ‘simultaneously’ as separate Unix processes and, using a message-passing mechanism, to communicate among themselves. They can be set to pursue an overall goal in a cooperative way. Moreover, several tasks can be given to each IS to be solved simultaneously, and the IS can switch from task to task according to dynamic priorities reflecting the urgency attached to the specific sub-tasks that emerge. The shell described here may also be used to test, within a distributed environment, some time-bounded reasoning techniques that are presently being developed. The paper has three main parts: a general overview of the UPShell (Section 1); a tutorial explaining, by means of examples, how to use the package (Section 2); and, finally, some considerations on the reasoning techniques used and future improvements (Sections 3–5).

Journal ArticleDOI
TL;DR: In this paper the 1KB defect classification system is presented, which is based on a hierarchical frame-based knowledge representation and a backward-chaining production rule system.
Abstract: This paper presents work undertaken as part of a project concerned with the development of a fully automated industrial radiographic inspection system, based on both conventional image-processing techniques for the detection and analysis of defects in the radiographic image, and intelligent knowledge-based (1KB) techniques for the classification and evaluation of defect data against the quality assurance requirements of the inspection process. In this paper the 1KB defect classification system is presented. This system is based on a hierarchical frame-based knowledge representation and a backward-chaining production rule system. Examples of the frame structures, frame taxonomies and the data-driven procedures, which maintain the knowledge base are given, along with an outline of the defect classification rules and the inference mechanism for dealing with uncertainty by means of confidence factors.

Journal ArticleDOI
TL;DR: Using case studies has two knowledge elicitation advantages: (1) the knowledge source is standardised and relatively unambiguous and (2) less domain expert involvement is required.
Abstract: A case study-based approach was used to develop the knowledge base of an expert system for marketing media class selection. Cases, in the context of business learning, are detailed, written descriptions of business problems and their resolution. An expert system rule set was developed for media class selection using standardised business case studies. The system developed was validated using another set of case studies. Using case studies has two knowledge elicitation advantages: (1) the knowledge source is standardised and relatively unambiguous and (2) less domain expert involvement is required.

Journal ArticleDOI
TL;DR: It is shown that certain types of knowledge found in management situations are more likely to lead to the successful adoption of management expert systems (MESs) than others, and that a potential exists for an alternative form of MES application.
Abstract: The purpose of this paper is to draw attention to some important barriers to the practical application of expert systems to management problems. By drawing attention to these barriers, we show two findings: (a) that certain types of knowledge found in management situations are more likely to lead to the successful adoption of management expert systems (MESs) than others; (b) that a potential exists for an alternative form of MES application. The first finding has implications for knowledge elicitation. We propose that MESs developed from academic knowledge, which we define in specific terms, are more likely to succeed than those developed from working with managers in the field. Alternatively, feasibility studies should include an analysis of the type of knowledge which a manager is capable of providing to ensure that suitable knowledge is available for knowledge elicitation purposes. The second finding has implications for the developers of MESs at both research and commercial levels. We suggest the need for a check-list MES application, capable of converting responses to strategic and operational questions into managerial actions.

Journal Article
TL;DR: The semantics of inheritance "hierarchies" with multiple inheritance and exceptions is discussed, and a partial semantics in terms of a number of structure types is defined.
Abstract: The semantics of inheritance "hierarchies" with multiple inheritance and exceptions is discussed, and a partial semantics in terms of a number of structure types is defined. Previously proposed inference systems for inheritance with exceptions are discussed. A new and improved inference system is proposed, using a fixed number of nonmonotonic inference rules. The hierarchy is viewed as a set of atomic propositions using the two relations isa (subsumption) and nisa (nonsubsumption). General results concerning systems of nonmonotonic inference rules can immediately be applied to the proposed inference system.

Journal ArticleDOI
TL;DR: It is described how two popular AI representation techniques—frames and production systems— can be usefully combined under a general AI object-oriented approach to problems which arise in the domain of hardware fault diagnosis.
Abstract: In this article we describe how two popular AI representation techniques—frames and production systems— can be usefully combined under a general AI object-oriented approach to problems which arise in the domain of hardware fault diagnosis. One of the main advantages of such a combination is that causal reasoning— crucial to the domain under consideration — can also be naturally and effectively represented. In order to put the combination of frames and production systems on a sound methodological footing, we first provide a knowledge engineering methodology which is an object-oriented re-interpretation of ontological analysis.

Journal ArticleDOI
TL;DR: A unification-based approach for verification of a knowledge base represented in the form of production rules and facts is proposed, which can determine conflicting, redundant, subsumed and circular rules; redundant if-conditions in rules; dead-end rules; and cycles and contradiction in rules.
Abstract: Knowledge base verification, a part of the validation process in expert system development, includes checking the knowledge base for completeness and consistency to guard against a variety of errors that can arise during the process of transferring expertise from a human expert to a computer system. Regardless of how an expert system is developed, its developers can profit from a systematic check of the knowledge base without gathering extensive data for test runs, even before the full reasoning mechanism is functioning. Until recently knowledge base verification has been largely ignored, which has led to expert systems with knowledge base errors and no safety factors for correctness. We propose a unification-based approach for verification of a knowledge base represented in the form of production rules and facts. This approach can determine conflicting, redundant, subsumed and circular rules; redundant if-conditions in rules; dead-end rules; and cycles and contradiction in rules.

Journal Article
TL;DR: In this paper, the authors look at some phenomena that recur during expert problem solving across domains including computer science, physics, chess, and mathematics, and several of the mechanisms which have been hypothesized to underlie performance in one domain are then used to explain the results found in the others.
Abstract: This article looks at some phenomena that recur during expert problem solving across domains including computer science, physics, chess, and mathematics. Several of the mechanisms which have been hypothesized to underlie performance in one domain are then used to explain the results found in the others. Competing explanations, mechanisms which are not fully specified, and untested empirical issues are also discussed.

Journal ArticleDOI
TL;DR: The growth in the use of expert systems is examined, the limitations and problems associated with present-day domain-specific expert systems are looked into, and a multi-domain expert system architecture is suggested as a solution to the problem of increasingly disjointed domain- specific expert systems resulting from uncontrolled proliferation.
Abstract: The current trend in expert system building is domain-specific, i.e. there is one expert system for each problem domain. The increased involvement of computers in the decision-making process will inevitably lead to increased demand for expert systems. Based on the current approach to expert systems building, there will be a further proliferation of domain-specific expert systems. This is because each application area produces an expert system tailored to its requirements. This manner of producing expert systems is inadequate and an increased expectation in the performance of expert systems will eventually call for a new approach to constructing them. This paper examines the growth in the use of expert systems, looks into the limitations and problems associated with present-day domain-specific expert systems and suggests a multi-domain expert system architecture as a solution to the problem of increasingly disjointed domain-specific expert systems resulting from uncontrolled proliferation.


Journal ArticleDOI
TL;DR: A system whereby an intensive care unit patient's condition can be monitored and assessed over time using mostly blood gas analysis data to evaluate the possible contribution of temporal medical reasoning from blood gas data is described.
Abstract: The aim of this paper is to describe a system whereby an intensive care unit patient's condition can be monitored and assessed over time using mostly blood gas analysis data. The first six sections analyse some major temporal reasoning approaches (with limited examples from other related areas) with the aim of selecting one for the task at hand. The last sections describe the PONJIP temporal blood gas analysis expert system with its main components, including user interfaces customised to the doctor's requirements. Since the overall aim of this paper is to describe an expert system used for the evaluation of the possible contribution of temporal medical reasoning from blood gas data, research specific to other application areas or data will not be covered here.

Journal ArticleDOI
TL;DR: Some of the problems encountered in developing a user interface for a commercial expert system are described and the emphasis is on the practical side of interface implementation while attempting to follow the many guidelines presented in the literature.
Abstract: This paper describes some of the problems encountered in developing a user interface for a commercial expert system. The emphasis is on the practical side of interface implementation while attempting to follow the many guidelines presented in the literature.

Journal Article
TL;DR: In this paper, the authors justify why Natural Language (NL) interaction is critical to the effective use of Expert Systems and describe what is needed and what has been done to support such interaction.
Abstract: The aim of this paper is to justify why Natural Language (NL) interaction, of a very rich functionality, is critical to the effective use of Expert Systems and to describe what is needed and what has been done to support such interaction. Interactive functions discussed here include defining terms, paraphrasing, correcting misconceptions, avoiding misconceptions, and modifying questions.