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The Balanced Tree and Its Utilization in Information Retrieval

IEEE Transactions on Electronic computers 1963年第6期EC-12卷 863-871页

作者： Landauer, Walter I. Computer Command and Control Company Philadelphia Pa. United States

To translate descriptors into memory locations a memory organization scheme called the balanced tree is introduced. The descriptors that describe the information to be stored or retrieved constitute quasi-inputs to the tree while the outputs are lists on which the information identified by the descriptors is stored. The balanced tree thus provides a stratagem to effect a fast information retrieval with a limited amount of serialized scanning. The algorithms for storing in and retrieving from the balanced tree are outlined. While in a randomly growing tree, the shape of the tree depends on the order of the input, the balanced tree is independent of this order. The expected number of rearrangement steps to keep the tree balanced was derived from combinatorial considerations. Numerical results were obtained by machine computations and are presented in this paper. COPYRIGHT © 1964—THE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, INC.

关键词： Information retrieval Contracts Information systems command and control systems Shape Distributed computing Content based retrieval Associative memory Large-scale systems Data processing

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File Structures for On-Line Systems 1

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1000年

作者： David Lefkovitz

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Automatic abstraction of real-time software and re-implementation in Ada

Automatic abstraction of real-time software and re-implement...

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1991 Conference on TRI-Ada: Today's Accomplishments;Tomorrow's Expectations, TRI-Ada 1991

作者： Prywes, Noah Lock, Evan Ge, Xiang Computer Command and Control Company 2300 Chestnut Street Ste. 230 PhiladelphiaPA19103 United States

ISBN: (纸本)0897914457

The paper reports on the underlying concepts of a system for software reverse engineering. Although, the immediate goal is translation from CMS-2 to Ada, the system is envisaged more broadly as a comprehensive environment for the software lifecycle: for initial development, maintenance, re-engineering and re-documentation. This environment must assure consistency at all times of design, programs and documentation. The paper describes the three phases of the system: Extracting design and documentation from existing software. User visualization and design/redesign of the software. Ada program generation from design/redesign. The first phase translates source programs into an object-oriented Entity-Relation-Attribute (ERA) diagram, which is the main vehicle for the graphic visualization. The translation uses a concise set of objects and relations. The second phase consists of user query and retrieval of subdiagrams that provide views of the software, needed to visualize or redesign specific aspects of the software. This phase is divided into in-the-large and in-the-small parts. The in-the-large part involves high level objects such as: systems, packages, tasks, procedures (or functions), external variables, input/output and comments that specify requirements or provide explanations. The user may need to use design tools that optimize the design. The in-the-small part consists of execution statements within an individual program unit. These are translated into the MODEL equational language and visualized through a petri-net like graph. The equational representation is considerably easier to comprehend, test and verify. Finally, the code generation phase uses the graphics and text from the previous phase to generate respective parts of Ada programs. There are three code generators, as follows: Packages are generated from object usage views. Tasks are generated from dataflow views. Individual procedures are generated from equations and petri-net like diagrams. The approac

关键词： Codes (symbols)

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Requirements on Ada reengineering technology from past, present and future systems

Requirements on Ada reengineering technology from past, pres...

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1992 Annual International Conference on TRI-Ada, TRI-Ada 1992

作者： Lock, Evan Prywes, Noah Computer Command and Control Company 2300 Chestnut Street PhiladelphiaPA19103 United States Department of Computer Science University of Pennsylvania PhiladelphiaPA United States

ISBN: (纸本)0897915291

The paper reviews the emerging approaches and technologies for reengineering software systems. The focus is on Ada as the target language. It presents an overview of the reengineering three-phase process: capture source software and its transformation to Ada;software understanding;and software redesign and reimplementation. For each phase, the paper describes the recognized requirements and the evolving technology. This is accompanied by references to the many ongoing research projects. The paper concludes by stressing the extensiveness of the reengineering problem and diversity of approaches. It urges convergence of ongoing developmental activities and pilot projects to achieve a demonstrated useful capability. © 1992 ACM.

关键词： Reengineering

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XVERSA: An integrated graphical and textual toolset for the specification and analysis of resource-bound real-time systems 8th

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Proceedings of the 1996 8th International Conference on computer Aided Verification, CAV'96

作者： Clarke, D. Ben-Abdallah, H. Lee, I. Xie, H.-L. Sokolsky, O. Department of Computer and Information Science University of Pennsylvania Philadelphia 19104-6389 PA United States Computer Command and Control Company Philadelphia 19104 PA United States

ISBN: (纸本)3540614745

We present XVERSA, a set of tools for the specification and analysis of resource-bound real-time systems. XVERSA facilitates the use of the Algebra of Communicating Shared Resources (ACSR), a real-time process algebra with explicit notions of resources and priority. A text based user interface supports syntax checking, analysis based on equivalence checking, state space exploration, and algebraic rewriting. A graphical user interface allows systems to be described and analyzed using intuitive pictorial representations of ACSR language elements. © Springer-Verlag Berlin Heidelberg 1996.

关键词： Real time systems

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On the Synthesis of Signal Switching Networks with Transient Blocking

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IEEE Transactions on Electronic computers 1967年第5期EC-16卷 637-641页

作者： Goldstein, Larry Joel Leibholz, Stephen W. Dept. of Mathematics Yale University New Haven Conn. United States Computer Command and Control Company Philadelphia Pa. United States

Signal switching networks with transient blocking are denned. The number of 2× 2 crossbars necessary to synthesize a signal switching network with transient blocking capable of performing all one-to-one connections of N inputs to N outputs is shown to be at least Nlog2N-N log2 e+(l/2) log2 N+log2 2+0(1) as N→∞. It is shown that this lower bound can never be attained for N > 2. An algorithm for building a network using at most 2N log2 N 2×2 crossbars is described. If N is a power of 2, N= 2m, then the algorithm described requires N log2 N–N+l 2×2 crossbars, which is close to the theoretical minimum. Generalizations of this work to networks performing an arbitrary permutation group of connections of inputs to outputs are indicated. Explicit results are obtained in the case of Abelian groups. Copyright © 1967 by The Institute of Electrical and Electronics Engineers, Inc.

关键词： Network synthesis Signal synthesis Multivalued logic Switches Boolean functions Wires Switching circuits Design automation Conferences Cities and towns

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Reverse software engineering of concurrent programs

Reverse software engineering of concurrent programs

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Proceedings of the Jerusalem Information Technology, 'Next Decade in Information Technology'

作者： X. Ge N. Prywes Computer Command and Control Company Philadelphia PA USA

The development of a system for reverse software engineering of real-time programs is described. It is addressed specifically to the US Navy's modernization of tactical and strategic systems. The approach is based on completely automatic translation from CMS-2 into a user-oriented nonprocedural specification language called MODEL. The user can better understand, maintain, and modernize the specification of programs in the MODEL language. There is an existing system for analysis, translation, and optimization in the conversion of MODEL to Ada. This completes the translation from the real-time CMS-2 programs to Ada programs. The overall system will use a powerful workstation with graphics.< >

关键词： Software engineering Military computing computer architecture Automation Hardware Investments Automatic testing Documentation Power system modeling computer aided software engineering

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Recovery of software design, state-machines and specifications from source code

Recovery of software design, state-machines and specificatio...

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IEEE International Conference on Engineering of Complex computer Systems

作者： N. Prywes P. Rehmet Computer Command and Control Company Philadelphia PA USA

While the end objective of the process described in this paper is recovery of software design, state-machines and specifications from source code, these capabilities depend on analysis and documentation of source code which are useful in themselves for software understanding. The paper therefore explains first the software analysis and construction of a software documentation database. It then follows with discussion of recovery of state machines and specifications. The focus in explaining the analysis of source code is in particular on the following. First, the recovery of design becomes significant when applied to large scale software. The source code may be in a large number of files which are analyzed sequentially. A database is constructed, where the code in each file is also used to update previously processed files. Second, the software understanding, as well as the state machines and specifications are based on discovery of a hierarchical software architecture that supports systematic software browsing and generation of state machines and specifications of respective components. The architecture discovery process must be human-guided through input of appropriate parameters that control the selection of software components based on including desired functions, critical operations and sizes. Finally, the state machines or specifications entities tend to be very voluminous. Depending on their intended use, their number can be reduced under user control.

关键词： Software design Databases Software tools computer architecture Software maintenance Tree graphs command and control systems Documentation Large-scale systems Software architecture

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Design of distributed communications system: a case study

Design of distributed communications system: a case study

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Proceedings of the November 18-20, 1969, fall joint computer conference

作者： N. Nisenoff Computer Command and Control Company Washington D.C.

The development of a concept for a Department of the Army Civilian Personnel Management and Manpower Data Reporting System and an Optimum Automatic Data Processing System was undertaken by computer command and control...

ISBN: (纸本)9781450379069

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A graphical property specification language

A graphical property specification language

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IEEE International Symposim on High Assurance Systems Engineering

作者： Insup Lee O. Sokolsky Real Time Systems Group University of Pennsylvania USA Computer Command and Control Company USA

Presents a language for the specification of high-level properties of real-time systems. The language is based on a temporal logic. Properties expressed as temporal logic formulae are known to be very obscure. In the design of the language, we tried to identify the sources of this and to make the expressions as easy to comprehend as possible. To enhance the flexibility of the language, we employ a two-level approach: an expert level and a user level. This us allows to hide the obscure formal notation from the user, and at the same time adjust the language to any desired problem domain. User-level expressions have a graphical notation, which brings out the structure of the expressions in a natural way and leads to an easier understanding of the formulae.

关键词： Specification languages Logic Clocks Delay Radio access networks

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