With text processing growing in importance as a computer application, the problems of sorting and merging will be encountered with increasing frequency. Various techniques have been used in ordering alphabetic strings...
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With text processing growing in importance as a computer application, the problems of sorting and merging will be encountered with increasing frequency. Various techniques have been used in ordering alphabetic strings, but text processing, involving upper- and lower-case alphabets, introduces an extra degree of freedom and complexity to the problem. This paper presents APL models of a solution for the generalized sorting problem.
A technique is presented for the succinct, precise description of solutions to data sharing problems in concurrent software systems. The technique is of use in modelling a software system during the architectural phas...
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A technique is presented for the succinct, precise description of solutions to data sharing problems in concurrent software systems. The technique is of use in modelling a software system during the architectural phase of its development, when components, component interfaces and component interactions are being defined. The precision of descriptions using the technique offers the opportunity to perform analysis during design and several approaches to analysis afforded by the technique are discussed.
An execution program is considered that supervises the cooperating tasks between independently running microcomputers. The supervisor consists of three main parts: the management of tasks, communication, and storage.
An execution program is considered that supervises the cooperating tasks between independently running microcomputers. The supervisor consists of three main parts: the management of tasks, communication, and storage.
A new modelling scheme capable of representing parallel systems with dynamic structure is discussed. An example is presented illustrating the model's use in studying correctness of process interaction is complex s...
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A new modelling scheme capable of representing parallel systems with dynamic structure is discussed. An example is presented illustrating the model's use in studying correctness of process interaction is complex software systems whose structure may change during system execution.
The ISI Delta Experiment is an effort to specify and verify a piece of real software of moderate complexity and size (roughly 1000 lines). This preliminary report describes (1) the Delta function, managing the editing...
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The ISI Delta Experiment is an effort to specify and verify a piece of real software of moderate complexity and size (roughly 1000 lines). This preliminary report describes (1) the Delta function, managing the editing of a single file by several users within an operational message processing system;(2) the formal specification of the Delta function in prose and in algebraic axioms;(3) the verification methodology in levels of (a) prose for the system interface level, (b) algebraic axioms for abstract data types, (c) recursive functions for major operations, (d) implementation of the recursive functions in PASCAL with the abstract data types, and (e) implementation of the PASCAL programs in BLISS;and (4) the experience gained in this experiment, both in specification and verification.
A methodology using attributed grammars representing the formal specification of distributed computing system software design is developed. This methodology provides a formal expression for synchronization, concurrent...
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A methodology using attributed grammars representing the formal specification of distributed computing system software design is developed. This methodology provides a formal expression for synchronization, concurrent processing and interprocess communication in the design of distributed computing system software using productions of attributed grammars. These productions can express sequencing, selection, recursion and concurrency in the system's activities, and can be used for expressing stepwise refinement of the design. The control flow of the software system is governed by the productions and the attributes of the symbols in the productions in the grammar. The formal specification of distributed computing system software design can also be used for consistency checking of the design and validation of implementation at run-time. An example is given to demonstrate this methodology.
A queueing analysis is presented of a pre-emptive, priority driven, timesliced dispatcher algorithm, typical of those found in many timesharing systems. A distinctive feature of the system being modeled is that a pree...
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A queueing analysis is presented of a pre-emptive, priority driven, timesliced dispatcher algorithm, typical of those found in many timesharing systems. A distinctive feature of the system being modeled is that a preempted task, when re-admitted to the dispatcher, is re-allocated a full timeslice rather than the residual. The combination of pre-emption, timeslice renewal and class dependent arrival and service rates, places the analysis beyond that of the well-known FB//N algorithms. The model is used to predict the behavior of the dispatcher algorithm under various workloads.
The conference proceedings contains 19 papers examining current developments in software engineering, in particular, requirements and specification methods. Reliable system performance is enhanced during development b...
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The conference proceedings contains 19 papers examining current developments in software engineering, in particular, requirements and specification methods. Reliable system performance is enhanced during development by detailed specifications that define constraints and record decisions that can be maintained throughout the development process. All papers are indexed separately.
General task scheduling for uniprocessor systems is an NP-hard problem. Many special cases, however, have simple optimal dynamic scheduling policies. Multiprocessor systems have NP-hard scheduling problems even for si...
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General task scheduling for uniprocessor systems is an NP-hard problem. Many special cases, however, have simple optimal dynamic scheduling policies. Multiprocessor systems have NP-hard scheduling problems even for simple special cases. This paper presents necessary conditions for optimal multiprocessor which produces only schedules meeting the necessary conditions. Experiments evaluating the algorithm are discussed. Further research directions leading to distributed implementations of multiprocessor scheduling policies are presented.
A unification is presented of two major previously unrelated specification techniques for abstract data types - the algebraic and abstract model approaches. Included is a disciplined specification methodology and its ...
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A unification is presented of two major previously unrelated specification techniques for abstract data types - the algebraic and abstract model approaches. Included is a disciplined specification methodology and its resultant proof obligation for an implementation. Several important issues are discussed, including equality, bounded objects and procedural implementation.
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