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The PegaSys System: pictures as formal documentation of large programs

Editor: Susan L. Graham Authors:

Mark Moriconi,

Dwight F. HareAuthors Info & Claims

ACM Transactions on Programming Languages and Systems (TOPLAS), Volume 8, Issue 4

Pages 524 - 546

https://doi.org/10.1145/6465.6478

Published: 01 August 1986 Publication History

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Abstract

PegsSys is an experimental system in which a user formally describes how a program is put together by means of a hierarchically structured collection of pictures, called formal dependency diagrams (FDDs). Icons in an FDD denote a wide range of data and control dependencies among the relatively coarse-grained entities contained in large programs. Dependencies considered atomic with respect to one level in a hierarchy can be decomposed into a number of dependencies at a lower level. Each dependency can be a predefined primitive of the FDD language or it can be defined by a PegaSys user in terms of the primitives.

A PegsSys user is given the illusion that logical formulas do not exist, even though PegaSys reasons about them internally. This involves (1) checking whether an FDD is meaningful syntactically, (2) determining whether hierarchical refinements of an FDD are methodologically sound, and (3) deciding whether an FDD hierarchy is logically consistent with the program that it is intended to describe. The techniques used to provide these capabilities are discussed along with the logical properties that enable PegaSys to maintain the user illusion.

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Cited By

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Moriconi MQian XRiemenschneider R(1995)Correct Architecture RefinementIEEE Transactions on Software Engineering10.1109/32.38597221:4(356-3)Online publication date: 1-Apr-1995
https://dl.acm.org/doi/10.1109/32.385972
Moriconi MQian X(1994)Correctness and composition of software architecturesACM SIGSOFT Software Engineering Notes10.1145/195274.19540319:5(164-174)Online publication date: 1-Dec-1994
https://dl.acm.org/doi/10.1145/195274.195403
Moriconi MQian XAdrion WWile D(1994)Correctness and composition of software architecturesProceedings of the 2nd ACM SIGSOFT symposium on Foundations of software engineering10.1145/193173.195403(164-174)Online publication date: 1-Dec-1994
https://dl.acm.org/doi/10.1145/193173.195403
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Index Terms

The PegaSys System: pictures as formal documentation of large programs

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This paper is an initial report on a system, called PegaSys, that supports a new visual paradigm for describing and manipulating programs and their designs. A program design is described by a hierarchically structured collection of graphical pictures. ...
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Reviews

Reviewer: Shahram Javey

The authors declare that data and control dependencies play an important role in programming in the large. (Examples of typical dependencies are “calls” dependencies between subprograms and “dataflow” dependencies between processes.) To address this problem, they've developed a software system called PegaSys. In PegaSys, the user supplies a pictorial description, called a Formal Dependency Diagram (FDD), of all the relevant dependencies of a program written in Ada. The PegaSys system will establish whether an FDD hierarchy is logically consistent with the program it is intended to describe. The pictures are meant to be a somehwat easier method for stating dependencies than the logical formulas which they denote. Indeed, the user is given the illusion that logical formulas do not exist. A major component of the PegaSys is its “program verifier,” which could be changed to support a different programming language. (The verifier is not intended to establish that a program satisfies its output requirement; instead it is a method for establishing that a program is consistent with its FDD hierarchy.) The authors provide a convincing and rigorous argument for why and how the PegaSys and all its major components work. This kind of comprehensive (and domain-specific) programming environment could prove to be an invaluable tool to the practicing software engineer. Overall, the paper is very well written, clear, and informative.

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cover image ACM Transactions on Programming Languages and Systems

ACM Transactions on Programming Languages and Systems Volume 8, Issue 4

Oct. 1986

190 pages

ISSN:0164-0925

EISSN:1558-4593

DOI:10.1145/6465

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Association for Computing Machinery

New York, NY, United States

Publication History

Published: 01 August 1986

Published in TOPLAS Volume 8, Issue 4

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Moriconi MQian XRiemenschneider R(1995)Correct Architecture RefinementIEEE Transactions on Software Engineering10.1109/32.38597221:4(356-3)Online publication date: 1-Apr-1995
https://dl.acm.org/doi/10.1109/32.385972
Moriconi MQian X(1994)Correctness and composition of software architecturesACM SIGSOFT Software Engineering Notes10.1145/195274.19540319:5(164-174)Online publication date: 1-Dec-1994
https://dl.acm.org/doi/10.1145/195274.195403
Moriconi MQian XAdrion WWile D(1994)Correctness and composition of software architecturesProceedings of the 2nd ACM SIGSOFT symposium on Foundations of software engineering10.1145/193173.195403(164-174)Online publication date: 1-Dec-1994
https://dl.acm.org/doi/10.1145/193173.195403
Ahmed SGelernter D(1992)A CASE environment for parallel programming[1992] Proceedings of the Fifth International Workshop on Computer-Aided Software Engineering10.1109/CASE.1992.200154(214-224)Online publication date: 1992
https://doi.org/10.1109/CASE.1992.200154
El-Kassas S(1991)Visual languages their definition and applications in system developmentMicroprocessing and Microprogramming10.1016/0165-6074(91)90375-432:1-5(383-391)Online publication date: Aug-1991
https://doi.org/10.1016/0165-6074(91)90375-4
Ambriola VCiancarini PCorradini ADeFrancesco N(1991)Towards innovative software engineering environmentsJournal of Systems and Software10.1016/0164-1212(91)90085-K14:1(17-29)Online publication date: 2-Jan-1991
https://dl.acm.org/doi/10.1016/0164-1212%2891%2990085-K
Lucas J(1991)Ein Visualisierungswerkzeug für die Wartung modularer ProgrammeTelekommunikation und multimediale Anwendungen der Informatik10.1007/978-3-642-77060-9_36(405-414)Online publication date: 1991
https://doi.org/10.1007/978-3-642-77060-9_36
Cleveland L(1989)A program understanding support environmentIBM Systems Journal10.1147/sj.282.032428:2(324-344)Online publication date: 1-Jun-1989
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Nakagawa AFutatsugi KDruffel LFairley DBjørner D(1989)Stepwise refinement process with modularityProceedings of the 11th international conference on Software engineering10.1145/74587.74611(166-177)Online publication date: 15-May-1989
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Nakagawa AFutatsugi K(1989)Stepwise Refinement Process With Modularity: An Algebraic Approach11th International Conference on Software Engineering10.1109/ICSE.1989.714417(166-177)Online publication date: 1989
https://doi.org/10.1109/ICSE.1989.714417
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PegaSys: A system for graphical explanation of program designs

PegaSys: A system for graphical explanation of program designs

Formal Verification of Ada Programs

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