Formal Semantics for Program Paths

Lermer, Karl; Fidge, Colin; Hayes, Ian J.

doi:10.1016/s1571-0661(04)81006-5

Cited by 4 publications

(7 citation statements)

References 19 publications

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“…Thus the following shows the equivalence of our results to those in [6]. We also defined functions expMng and bexpMng to translate an expression (type exp or bexp -which we will call a syntactic expression) to the corresponding function of type state → value or state → bool (which we will call a semantic expression, calling it the "meaning" of the syntactic expression).…”

Section: Frames and Variable Namesmentioning

confidence: 52%

“…Strongest postconditions have been discussed by a number of authors, cited in [6]. In [6], Lermer, Fidge & Hayes give the strongest postcondition semantics, as well as the weakest liberal precondition semantics, of the commands they define, and we will refer to some of these later.…”

Section: Strongest Postconditionsmentioning

confidence: 99%

“…In [6], Lermer, Fidge & Hayes give the strongest postcondition semantics, as well as the weakest liberal precondition semantics, of the commands they define, and we will refer to some of these later. Meanwhile we give its definition in Isabelle, and that of what they call "sp-refinement".…”

Section: Strongest Postconditionsmentioning

confidence: 99%

“…In fact it was trivial to prove (as wlp_slp_ref) that strongest post-condition refinement is equivalent to partial-correctness refinement ([6, Thm 6.1(vii)]). This is readily explained by the Galois connection between the weakest liberal precondition and the strongest postcondition functions (wlp_slp_gal, of which Theorem 6.1(v) and (vi) of [6] are easy corollaries).…”

Section: Strongest Postconditionsmentioning

confidence: 99%

“…In [6], Lermer, Fidge & Hayes considered the semantics of program execution, focussing on control-flow paths. They consider weakest liberal preconditions, and also discuss strongest postconditions.…”

Section: Introductionmentioning

confidence: 99%

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Formalising General Correctness

Dawson

2004

Electronic Notes in Theoretical Computer Science

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Section: Frames and Variable Namesmentioning

confidence: 52%

Section: Strongest Postconditionsmentioning

confidence: 99%

Section: Strongest Postconditionsmentioning

confidence: 99%

Section: Strongest Postconditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Formalising General Correctness

Dawson

2004

Electronic Notes in Theoretical Computer Science

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Linear Approximation of Execution-Time Constraints

2003

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Abstract. This paper defines an algorithm for predicting worst-case and best-case execution times, and determining execution-time constraints of control-flow paths through real-time programs using their partial correctness semantics. The algorithm produces a linear approximation of path traversal conditions, worst-case and best-case execution times and strongest postconditions for timed paths in abstract real-time programs. Also shown are techniques for determining the set of control-flow paths with decidable worst-case and best-case execution times. The approach is based on a weakest liberal precondition semantics and relies on supremum and infimum calculations similar to standard computations from linear programming and Presburger arithmetic. The methodology is applicable to any executable language with a predicate transformer semantics and hence provides a verification basis for both high-level language and assembly code execution-time analysis.

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Procedures and parameters in the real-time program refinement calculus

Hayes

2007

Science of Computer Programming

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The real-time refinement calculus is a formal method for the systematic derivation of real-time programs from real-time specifications in a style similar to the non-real-time refinement calculi of Back and Morgan. In this paper we extend the realtime refinement calculus with procedures and provide refinement rules for refining real-time specifications to procedure calls. A real-time specification can include constraints on, not only what outputs are produced, but also when they are produced. The derived programs can also include time constraints on when certain points in the program must be reached; these are expressed in the form of deadline commands. Such programs are machine independent. An important consequence of the approach taken is that, not only are the specifications machine independent, but the whole refinement process is machine independent. To implement the machine independent code on a target machine one has a separate task of showing that the compiled machine code will reach all its deadlines before they expire.For real-time programs, externally observable input and output variables are essential. These differ from local variables in that their values are observable over the duration of the execution of the program. Hence procedures require input and output parameter mechanisms that are references to the actual parameters so that changes to external inputs are observable within the procedure and changes to output parameters are externally observable. In addition, we allow value and result parameters. These may be auxiliary parameters, which are used for reasoning about the correctness of real-time programs as well as in the expression of timing deadlines, but do not lead to any code being generated for them by a compiler.

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Formal Semantics for Program Paths

Cited by 4 publications

References 19 publications

Formalising General Correctness

Formalising General Correctness

Linear Approximation of Execution-Time Constraints

Procedures and parameters in the real-time program refinement calculus

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