Guarded commands, non-determinacy and a calculus for the derivation of programs

  • Edsger W. Dijkstra
Chapter 2.: Program Development
Part of the Lecture Notes in Computer Science book series (LNCS, volume 46)


So-called "guarded commands" are introduced as a building block for alternative and repetitive constructs that allow non-deterministic program components for which at least the activity evoked, but possibly even the final state, is not necessarily uniquely determined by the initial state. For the formal derivation of programs expressed in terms of these constructs, a calculus will be shown.


programming languages sequencing primitives program semantics programming language semantics non-determinacy case-construction repetition termination correctness proof derivation of programs programming methodology 


4.20 4.22 


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  1. [1]
    Hoare, C.A.R., An Axiomatic Basis for Computer Programming, Comm.ACM 12 (Oct. 1969) 576–583.Google Scholar
  2. [2]
    Naur, Peter, (Ed.) Report on the Algorithmic Language ALGOL 60, Comm.ACM 3 (May 1960) 299–314Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1976

Authors and Affiliations

  • Edsger W. Dijkstra
    • 1
  1. 1.BURROUGHSNUENENThe Netherlands

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