There is a general agreement among theoretical computing scientists that a programming language, or its underlying computational paradigm, may be clarified by a mathematical investigation of its formal semantics. The...
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There is a general agreement among theoretical computing scientists that a programming language, or its underlying computational paradigm, may be clarified by a mathematical investigation of its formal semantics. There are at least 3 approaches to the definition of the required semantics. The algebraic approach is presented as a group of algebraic equations, like the axioms of group theory. The derivation of operational semantics from algebraic laws is examined. First, the transition relation is defined by an inequation, and then the individual clauses of the operational semantics are derived one by one by algebraic reasoning. Consistency is thereby guaranteed, although the question of completeness is left open. The method is illustrated on 2 languages. One is a large subset of CSP, while the other is a notational variant of Dijkstra's Language. A combination of these languages provides a basis for the treatment of the transputer language OCCAM.
This paper describes the use of Ruby, a language of functions and relations, to develop serialised implementations of array-based architectures. Our Ruby expressions contain parameters which can be varied to produce a...
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This paper describes the use of Ruby, a language of functions and relations, to develop serialised implementations of array-based architectures. Our Ruby expressions contain parameters which can be varied to produce a wide range of designs with different space-time trade-offs. Such expressions can be obtained by applying correctness-preserving transformations to an initial simple description. This approach provides a unified treatment of serialisation schemes similar to LPGS (Locally Parallel Globally Sequential) and LSGP (Locally Sequential Globally Parallel) partitioning methods, and will be illustrated by the development of a variety of circuits for convolution.
This paper demonstrates how reduction to normal form can help in the design of a correct compiler for Dijkstra's guarded command language. The compilation strategy is to transform a source program, by a series of ...
This paper demonstrates how reduction to normal form can help in the design of a correct compiler for Dijkstra's guarded command language. The compilation strategy is to transform a source program, by a series of algebraic manipulations, into a normal form that describes the behaviour of a stored-program computer. Each transformation eliminates high-level language constructs in favour of lower-level constructs. The correctness of the compiler follows from the correctness of each of the algebraic transformations.
An overview is given of D-I algebra, an algebra for the specification of the safety and progress properties of delay-insensitive circuits in terms of voltage-level transitions on wires. The algebraic laws make it poss...
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The authors describe a method for speeding up divide-and-conquer algorithms with a hardware coprocessor, using sorting as an example. The method employs a conventional processor for the 'divide' and 'merge...
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An occam program is usually translated into a machine program executed in parallel with a set of system processes such as communication protocol and scheduler, where the target program appears in a form which cannot b...
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A prototype proof system for "W: A Logic for Z" has been produced using the 2OBJ metalogical theorem-prover. 2OBJ permits an encoding which is very similar in structure to that of W, and the details are pres...
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We present a methodology for the formal specification and development of software systems using Z and the refinement calculus. The methodology combines the data structuring capabilities and the codified discrete mathe...
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The purpose of this paper is to introduce a notation for expressing the requirements of time-critical systems and a calculus for reasoning about them. The Actions, Events and States of a system are represented by sets...
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An overview is given of D-I algebra, an algebra for the specification of the safety and progress properties of delay-insensitive circuits in terms of voltage-level transitions on wires. The algebraic laws make it poss...
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An overview is given of D-I algebra, an algebra for the specification of the safety and progress properties of delay-insensitive circuits in terms of voltage-level transitions on wires. The algebraic laws make it possible to specify circuits concisely and facilitate the verification of designs. Individual components can be composed into circuits in which signals along internal wires are hidden from the environment. A delay-insensitive approach has been successfully applied to several nontrivial designs, such as the design of a packet router and the design of a constant response-time stack, and D-I algebra has played an important role both in suggesting decompositions and in verifying them.< >
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