We consider the problem of proving correctness properties for concurrent systems with features such as higher-order communication and dynamic resource generation. As examples we consider operational models of security...
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(纸本)0818682558
We consider the problem of proving correctness properties for concurrent systems with features such as higher-order communication and dynamic resource generation. As examples we consider operational models of security and authentication protocols based on the higher-order pi-calculus. Key features such as nonces/time stamps, encryption/decryption, and key generation are modelled using channel name generation and second-order process communication. A temporal logic based on the modal mu-calculus is used to express secrecy and authenticity. Extensions include function space constructions to deal with process input and output. Contravariant recursion can be dealt with in two different ways, of which one, an iterative solution, is discussed in the paper. We propose a predicate of trust in a monotonically increasing set of channels as an example, and establish structural decomposition principles for this predicate for concurrent composition and local channel declaration. On this basis a type system for trust inference can be derived quite easily.
After analyzing the steps leading to the development of a program for a microprocessor based control system it is found that the programming language to be used should not obscure to the designer the precise operation...
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After analyzing the steps leading to the development of a program for a microprocessor based control system it is found that the programming language to be used should not obscure to the designer the precise operation of the system. It also should reflect the symbolism of the system analyst. programming in an assembly-like language with the aided potential for calling bit-oriented data structures by name, is found to be adequate and can be achieved by using a preprocessing pass. The source text is translated into regular assembler text. This idea is applied to programming INTEL's 8080.
Documentation standards have been developed by a variety of organizations, ranging from government to professional societies to individual companies. Although there are differences among these standards, there is fair...
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Documentation standards have been developed by a variety of organizations, ranging from government to professional societies to individual companies. Although there are differences among these standards, there is fairly general agreement on the content of documentation and on the need for good documentation. There is less agreement on the extent of verification and qualification that is implied by documentation or on the responsibility for doing the verification. Much of the variation between documentation standards reflects the needs of the persons preparing the standards. The user of computer programs must satisfy himself that the techniques he is using perform properly and are appropriate to the job. The professional societies have a role to perform in developing standards and providing experience in their use.
A time-sharing system was studied and its performance under live loads was analyzed in detail. As use of the system grew its parameters were altered to optimize performance. Two basically different sets of parameters ...
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A time-sharing system was studied and its performance under live loads was analyzed in detail. As use of the system grew its parameters were altered to optimize performance. Two basically different sets of parameters were tried. The action taken varied as the load changed, but in general one of these parameter sets gave performance closer to that desiered by the user.
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 time-sharing executive has been developed to run on a floppy disk based PDP 11/10 system under the RT-11 single job monitor. The intent of the system is to allow several users access to a suite of reentry data colle...
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A time-sharing executive has been developed to run on a floppy disk based PDP 11/10 system under the RT-11 single job monitor. The intent of the system is to allow several users access to a suite of reentry data collection and data processing routines. Time-sharing is performed by switching jobs after initiating an input or output request via the . READC and . WRITC programmed request supported by RT-11. The system occupies 6K of memory for the program module. An additional 3K of core is required for the device buffers and the job status table. As such, a minimum of 9K is required to operate the system. System utility routines include a spooled printer, system data and time reading and setting, a line text editor, capability to rename and delete file, and an interval time for ″stopwatch″ timing of experimental events.
Allocation of paged memory in a multiprogramming environment is considered. Based on uniprogramming studies, such as statistical observations of actual programs as well as primitive program models, a memory space shar...
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Allocation of paged memory in a multiprogramming environment is considered. Based on uniprogramming studies, such as statistical observations of actual programs as well as primitive program models, a memory space sharing algorithm is constructed which selects a program to lose a page when a new page is demanded.
A time-sharing technique was designed and a system was developed to greatly improve the efficiency of man and machine time utilization in the development and running of simulation programs. The general approach to the...
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A time-sharing technique was designed and a system was developed to greatly improve the efficiency of man and machine time utilization in the development and running of simulation programs. The general approach to the problem is presented along with goals, advantages, and disadvantages. Several aspects of the system are explored in detail.
Balancing interpagefault lifetime (L) against page swap time (S) has always been a performance criterion of great intuitive appeal. This paper shows that, under normal conditions, controlling the memory policy paramet...
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Balancing interpagefault lifetime (L) against page swap time (S) has always been a performance criterion of great intuitive appeal. This paper shows that, under normal conditions, controlling the memory policy parameter to enforce the constraint L greater than equivalent to S, and allowing the multiprogramming load to rise as high as demand warrants without violating this constraint, will produce a load slightly higher than optimum. Equivalently, using the criterion L equals uS for some u slightly larger than 1 will approximate an optimal load. Using simulations, this criterion is compared with two others reported in the literature, namely the ″knee criterion″ and the 50% criterion. Since no practical implementation of the knee criterion is known, the L equals S criterion is the most attractive of the three.
This article generalizes the concept of pipelining to increase throughput, processing speed, resource utilization and reliability. Its wide application spectrum is demonstrated and major design problems such as sequen...
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This article generalizes the concept of pipelining to increase throughput, processing speed, resource utilization and reliability. Its wide application spectrum is demonstrated and major design problems such as sequencing, reconfiguration, etc. , are indicated. A scheme called the dynamic sequencing and segmentation model (DSSM) is proposed as a solution for providing efficient sequencing with very low overhead. The model is analyzed under various realistic environments and its performance is evaluated.
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