Systematic software development using VDM (2nd ed.)
Systematic software development using VDM (2nd ed.)
Programming from specifications
Programming from specifications
The B-book: assigning programs to meanings
The B-book: assigning programs to meanings
Algorithm Refinement with Read and Write Frames
FME '93 Proceedings of the First International Symposium of Formal Methods Europe on Industrial-Strength Formal Methods
Structural Embeddings: Mechanization with Method
FM '99 Proceedings of the Wold Congress on Formal Methods in the Development of Computing Systems-Volume I - Volume I
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VDM and B are two 驴model-oriented驴 formal methods. Each gives a notation for the specification of systems as state machines in terms of a set of states with operations defined as relations on that set. Each has a notion of refinement of data and operations based on the principles of reduction of nondeterminism and increase in definedness. This paper makes a comparison of the two notations through an example of a communications protocol previously formalized in [1]. Two abstractions and two reifications of the original specification are given. Particular attention is paid to three areas where the notations differ: the use of postconditions that assume the invariant as opposed to postconditions that enforce it; the explicit 驴framing驴 of operations as opposed to the 驴minimal frame驴 approach; and the use of relational postconditions as opposed to generalized substitutions.