Presented are early developments of storage management techniques, particularly those used in OS/360. Innovations introduced by systems that use dynamic address translation are traced. The impact of these techniques o...
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Presented are early developments of storage management techniques, particularly those used in OS/360. Innovations introduced by systems that use dynamic address translation are traced. The impact of these techniques on current IBM System/370 Operating Systems is described.
Developing advanced structuring techniques has always been of great importance for computer science and practice. Many structuring approaches are used to help capture certain characteristics of applications: group com...
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Developing advanced structuring techniques has always been of great importance for computer science and practice. Many structuring approaches are used to help capture certain characteristics of applications: group communications, replication features, file services, etc. Associating fault tolerance measures with structuring units allows us to benefit from state and behaviour encapsulation while designing dependable systems. Procedures were among the first general techniques intended for structuring application software. They reflect both the static and dynamic structures of sequential systems (a stack of procedure contests of nested calls represents the state of program execution). The situation is much more complex in concurrent systems, in which the states of several concurrent components should be taken into consideration while describing system behaviour in general, and its fault tolerance in particular. The purpose of this survey is to outline recent trends in developing approaches to structuring competitive and cooperative concurrent systems, together with corresponding fault tolerance techniques, and to discuss different directions of research in this area and their interrelations.
We explore the design space of implementing suffix tree algorithms in the functional paradigm. We review the linear time and space algorithms of McCreight and Ukkonen. Based on a new terminology of nested suffixes and...
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We explore the design space of implementing suffix tree algorithms in the functional paradigm. We review the linear time and space algorithms of McCreight and Ukkonen. Based on a new terminology of nested suffixes and nested prefixes, we give a simpler and more declarative explanation of these algorithms than was previously known. We design two ''naive'' versions of these algorithms which are not linear time, but use simpler data structures, and can be implemented in a purely functional style. Furthermore, we present a new, ''lazy'' suffix tree construction which is even simpler. We evaluate both imperative and functional implementations of these algorithms. Our results show that the naive algorithms perform very favourably, and in particular, the lazy construction compares very well to all the others.
Much research has been devoted to the problems of detecting program unstructuredness, and numerous ways of restructuring them have been proposed. These studies can be divided into 3 categories. First, most of the pa...
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Much research has been devoted to the problems of detecting program unstructuredness, and numerous ways of restructuring them have been proposed. These studies can be divided into 3 categories. First, most of the papers are based on heuristic or intuitive arguments. The 2nd approach employs the concept of reducibility of program schemes. A 3rd method uses the concept of succession paths in flowgraphs to define the minimum module related with a given node. This approach appears to be the most promising because it produces simple but working algorithms. Urschler (1975), for example, proposed an efficient algorithm for structuring programs automatically. Here, the conditions for unstructuredness are studied in terms of succession paths. Multiple entries and exits are formally defined, and it is shown that 2 simple conditions are sufficient for the detection of unstructuredness. One of these is that a module will be unstructured if the node is in one of its branches but not in the corresponding skeleton.
The aerodynamic design process is now strongly influenced by the application of advanced computational tools due mainly to recent advances in computer capabilities. Today’s aerodynamic analysis codes require large am...
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In this paper, results on extensions of adaptive observer design to state and/or parameter nonlinearities are discussed at the light of a canonical structure for rank observable systems and a related available observe...
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AbstractHADES is a command program designed to aid programmers and authors involved in writing systems with an inherently high degree of structuring. It presents the system being developed in a hierarchical fashion, e...
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AbstractHADES is a command program designed to aid programmers and authors involved in writing systems with an inherently high degree of structuring. It presents the system being developed in a hierarchical fashion, encouraging a top down approach to its design, and alleviates many of the problems experienced with traditional filing systems. Unlike other programming environment systems, the utility programs and tools do not have to be ‘integrated’ into the system, which means that new and existing tools can be quickly and easily added. This results in a rich set of operations implemented at very low *** paper outlines some of the problems that arise with traditional filing systems from the point of view of software development, and then presents the approach adopted by HADES. This is followed by a discussion of the strengths and weaknesses of the result and some reflections on the lessons that have been lea
Certain graph theoretic problems dealing with the testing of structured programs are treated. A structured digraph is a digraph that represents a structured program. A labelling procedure which characterizes structure...
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Certain graph theoretic problems dealing with the testing of structured programs are treated. A structured digraph is a digraph that represents a structured program. A labelling procedure which characterizes structured digraphs is described. An efficient algorithm for finding a minimum path cover for the vertices of digraphs that belong to an important family of structured digraphs is given. To model interactions among code segments the notions of `required pairs" and `must pairs" are introduced and the corresponding constrained path cover problems are shown to be NP-complete even for acyclic structured digraphs.
Structural modes as for example decoupling of a mechanical subsystem are in general unwanted effects in high precision positioning systems. This paper proposes a well designed decoupling mechanism as a design choice t...
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This paper presents a static approach to exception handling. The static approach is proposed as a consequence of an examination of existing language constructs for exception handling in which several trouble spots hav...
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This paper presents a static approach to exception handling. The static approach is proposed as a consequence of an examination of existing language constructs for exception handling in which several trouble spots have been revealed. The static approach consists basically of one concept, namely the sequel concept. Although the sequel concept is sufficient to specify exception handling within a program, one additional concept is introduced, namely the derived definition concept that is introduced as a generalization of the derived type and generic concepts from Ada. The main advantages of the static approach are first that it is truly static as opposed to the existing language constructs in which dynamic association is used in some way or another; and, secondly, the language constructs for exception handling are simple, easy to implement and based on familiar concepts.
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