The issue of executing concurrent transactions reliably in a multidatabase system is addressed. Our formalization assumes the most pessimistic scenario where individual database managers that make up the multidatabase...
We consider projections of semicomputable relations on abstract structures We show that they arise in several contexts, including nondeterministic extensions of while programs with arrays by means of arbitrary initial...
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We consider projections of semicomputable relations on abstract structures We show that they arise in several contexts, including nondeterministic extensions of while programs with arrays by means of arbitrary initializations and random assignments. They form a basis for an investigation of the concept of algorithmic specifications of relations with nondeterministic search. An important technique in this investigation is the study of computation trees for imperative programs, in order to prove characterization theorems for semicomputable sets, of a form first developed by E. Engeler.
作者：
Raymond JacobyYoshihiro TohmaTOSHIBA Corporation
Systems & Software Engineering Laboratory Saiwat-ku Kawasaki-shi 210 Japan and Department of Computer Science Tokyo Institute of Technology Ookayama 2-12-1 Meguro-Ku Tokyo Department of Computer Science
Tokyo Institute of Technology Ookayama 2-12-1 Meguro-Ku Tokyo
作者：
KING, JFBARTON, DEJ. Fred King:is the manager of the Advanced Technology Department for Unisys in Reston
Virginia. He earned his Ph.D. in mathematics from the University of Houston in 1977. He has been principal investigator of research projects in knowledge engineering pattern recognition and heuristic problem-solving. Efforts include the development of a multi-temporal multispectral classifier for identifying graincrops using LANDSAT satellite imagery data for NASA. Also as a member of the research team for a NCI study with Baylor College of Medicine and NASA he helped develop techniques for detection of carcinoma using multispectral microphotometer scans of lung tissue. He established and became technical director of the AI Laboratory for Ford Aerospace where he developed expert scheduling modeling and knowledge acquisition systems for NASA. Since joining Unisys in 1985 he has led the development of object-oriented programming environments blackboard architectures data fusion techniques using neural networks and intelligent data base systems. Douglas E. Barton:is manager of Logistics Information Systems for Unisys in Reston
Virginia. He earned his B.A. degree in computer science from the College of William and Mary in 1978 and did postgraduate work in London as a Drapers Company scholar. Since joining Unisys in 1981 his work has concentrated on program management and software engineering of large scale data base management systems and design and implementation of knowledge-based systems in planning and logistics. As chairman of the Logistics Data Subcommittee of the National Security Industrial Association (NSIA) he led an industry initiative which examined concepts in knowledge-based systems in military logistics. His responsibilities also include evaluation development and tailoring of software engineering standards and procedures for data base and knowledge-based systems. He is currently program manager of the Navigation Information Management System which provides support to the Fleet Ballistic Missile Progr
A valuable technique during concept development is rapid prototyping of software for key design components. This approach is particularly useful when the optimum design approach is not readily apparent or several know...
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A valuable technique during concept development is rapid prototyping of software for key design components. This approach is particularly useful when the optimum design approach is not readily apparent or several known alternatives need to be rapidly evaluated. A problem inherent in rapid prototyping is the lack of a "target system" with which to interface. Some alternatives are to develop test driver libraries, integrate the prototype with an existing working simulator, or build one for the specific problem. This paper presents a unique approach to concept development using rapid prototyping for concept development and scenario-based simulation for concept verification. The rapid prototyping environment, derived from artificial intelligence technology, is based on a blackboard architecture. The rapid prototype simulation capability is provided through an object-oriented modeling environment. It is shown how both simulation and blackboard technologies are used collectively to rapidly gain insight into a tenacious problem. A specific example will be discussed where this approach was used to evolve the logic of a mission controller for an autonomous underwater vehicle.
Theoretical results for identifying unnecessary inferences are discussed in the context of the use of a completion-procedure-based approach toward automated reasoning. The notion of a general superposition is introduc...
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Theoretical results for identifying unnecessary inferences are discussed in the context of the use of a completion-procedure-based approach toward automated reasoning. The notion of a general superposition is introduced and it is proved that in a completion procedure, once a general superposition is considered, all its instances are unnecessary inferences and, thus, do not have to be considered. It is also shown that this result can be combined with another criterion, called the prime superposition criterion, proposed by Kapur, Musser, and Narendran, thus implying that prime and general superpositions are sufficient. These results should be applicable to other approaches toward automated reasoning, too. These criteria can be effectively implemented, and their implementation has resulted in automatically proving instances of Jacobson's theorem (also known as the ring commutativity problems) usingRRL (Rewrite Rule Laboratory), a theorem prover based on rewriting techniques and completion.
The idea of duality in control theory results from the striking symmetry between the properties of controllability and observability of linear systems. It is well known that the duality between the optimum regulator p...
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The idea of duality in control theory results from the striking symmetry between the properties of controllability and observability of linear systems. It is well known that the duality between the optimum regulator problem (ORP) and the optimum estimator problem (OEP) can be used to obtain properties of the OEP from the ORP and vice versa; moreover, computer programs designed for ORPscan be used for solving OEPsand vice versa. Emphasis is laid on the duality between a controller design technique, based on frequency–shaped performance indices, the extended optimum regulator problem, and a technique for solving the optimum state estimation problem for an LT1 system with additive coloured noise, the extended optimum estimator problem.
A new method is presented for reasoning with constraints on the three orientation parameters of an object which arise from the identification of features discovered in a single image. The method uses a geometrical mod...
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A new method is presented for reasoning with constraints on the three orientation parameters of an object which arise from the identification of features discovered in a single image. The method uses a geometrical model of the object and a tetrahedral representation of view-direction. The final angle parameter, the roll angle, is computed for each view direction. This method is subject to errors from the data and the assumptions inherent in the use of view directions. These errors are taken into account by considering upper and lower bounds on the roll angle. A method is presented for using constraints on the orientation parameters to prune the search for a consistent set of labelled image lines and to guide an iterative inversion of the view perspective.
”All animals are equal, but some animals are more equal than others”, Antrum Farm, George Orwell. Object Orientation is a current hot theme for researchers and developers of distributed systems. This paper reviews t...
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The distributed systems group in Trinity have been concerned with fault tolerance for a number years and are now turning our attention to the topic with renewed interest (and urgency). Specifically we are concerned to...
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