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The practice of parallel computing seems to be in a crises. The parallel processing has not become a common matter and the “second computer revolution” that should have been caused by the replacement of sequential computers by parallel ones is not to happen in near future. The only hope for overcoming the parallel computing crisis lays in the development of computational complexity theory. This offers...
Fuzzy logic is analyzed from the point of view of formal logic; the underlying calculi and their proporties are surveyed and applications are discussed.
We discuss recent research evaluating the benefits of certain link labellings in processor networks. Such a labelling, called Sense of Direction or SoD, allows processors to communicate more efficiently with each other, and to exploit topological properties of the network algorithmically. We shall define sense of direction for several specific classes of network, and show how the election problem...
This paper reasons about the need to seek for particular kinds of models of computation that imply stronger computability than the classical models. A possible such a model, constituting a chaotic dynamical system is presented. This model, which we term as the analog shift map, when viewed as a computational model has super-Turing power and is equivalent to neural networks and the class of analog...
We prove that a class of architectures called NARX neural networks, popular in control applications and other problems, are at least as powerful as fully connected recurrent neural networks. Recent results have shown that fully connected networks are Turing equivalent. Building on those results, we prove that NARX networks are also universal computation devices. NARX networks have a limited feedback...
Database Systems have come a long way in the 30 years or so of their existence. However, despite the relative success, there are large areas of end-user requirements that current systems just cannot address. This paper identifies key features of database technology, analyses the end-user requirement against these key features and thus highlights inadequacies. The opportunities of distribution and...
The Information Systems of the future will be distributed, heterogeneous and open. They will require the integration of five key technologies — databases, multimedia, object orientation, artificial intelligence and telecommunications. This paper explains the contribution of these technologies to the vision of the future and how they can be integrated. Key technical challenges and open research issues...
Throughout the 1980s and 1990s, a significant proportion of database research activity has been directed towards extending the modelling and programming facilities supported by database systems. This paper looks into the motivation for such activity, characterises and summarises representative proposals for extensions, and presents a concrete example of a database system incorporating a range of advanced...
This paper describes some of the major changes in information systems (IS) requirements in the 90s and compares them with recent and planned changes to SSADM and PRINCE (for IS development and IS project management respectively). Background is provided describing CCTA's role in UK government and its rationale in developing public domain methods.
This paper discusses the use of formal methods in the light of experience gained from two industrial projects using the B Abstract Machine Notation. An simple example is presented which demonstrates the use of formal specification, refinement and proof in the B-Method, and this is compared with a similar development in VDM. The role of fully formal proof is considered and, in particular, the construction...
This paper presents an approach to the development of safetycritical real-time systems linking from the Requirements Language developed in the ESPRIT Project ProCoS to the Temporal Language of Transitions (TLT) specification language developed at Siemens Corporate Research. A system is defined by a conventional mathematical model for a dynamic system where application specific states denote functions...
In this paper I answer the question how evolving algebras can be used for the design and analysis of complex hardware and software systems. I present the salient features of this new method and illustrate them through several examples from my work on specification and verification of programming languages, compilers, protocols and architectures. The definition of a mathematical model for Hennessy...
This paper summarizes works done at I.N.T. with Chorus Operating System. It briefly describes Chorus' concepts and abstractions useful to understand our work. Then it focuses on Chorus micro-kernel capabilities and explains how these capabilities have been used to make an experiment allowing the cohabitation between the Chorus micro-kernel and the Macintosh Operating system. Then, it...
Highly parallel scalable multiprocessing systems are powerful tools for solving large-scale scientific and engineering problems. Languages such as Vienna Fortran and High Performance Fortran (HPF) have been introduced to allow the programming of these machines at a relatively high level of abstraction, based on the data-parallel Single-Program-Multiple-Data (SPMD) model. Their main features focus...
Internet is continuing to spread like wildfire and is used more and more for networked multimedia systems, often called hypermedia systems. In this paper we analyze some aspects of modern hypermedia systems, concentrate on what are often called “second generation tools” and discuss electronic publishing as one of their applications in some detail.
Modern Geographic Information Systems should provide powerful user-oriented information systems for maintenance and analyses of spatially referenced data. The first part of the paper gives a gentle introduction into the area of GIS, their applications and provides a short overview of fundamental features in traditional GIS. Problems and deficiencies in the traditional point of view on GIS are indicated...
Over the last few years there has been a phenomenal growth in the use of WWW (World Wide Web) for a wide variety of purposes from advertising and publicity, to collaborative work and teaching. Because it is so easy to set up a server, there are almost as many web philosophies, uses and page designs as there are web pages. Of course some of these are better than others and within CISD we believe...
In this paper, we present several improvements of an algorithm for a higher-order unification based on the calculus of explicit substitutions. The main difference between our algorithm and the already known version is, that we try to postpone normalisation of λσ-terms as long as possible, i.e. until some information of these λσ-terms is necessary for the next step of the unification algorithm.
Two time dimensions are usually considered in temporal databases: transaction-time, which tells when an event is recorded in a database, and valid-time, which tells when an event occurs, occurred or is expected to occur in the real world. Transaction-time is defined by the system and can only grow, since it records the time of successive transactions. This peculiarity makes it difficult to adapt traditional...
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