Titlebook: Constructing Correct Software; D. John Cooke Textbook 19981st edition Springer-Verlag London 1998 Formal Development.algorithms.design.dev

placebo-effect

禁令

The Specification of Functions II,y of computable functions tells us that there really is nothing else which . be computed — all computations and data values can be encoded into single integers. But not all data . like a single integer and we want to be able perform calculations which act on (uncoded) data in the form that we common

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袋鼠

Algorithm Extraction,ntation; for the implementation of a program which, given suitable data, can be executed to calculate the function. In most cases we shall have to use a mix of different design strategies for transformation and refinement. So far we have only met (reversible) transformations — refinement comes later

纪念

Specifications Revisited (Quantifications etc.),re more complicated than others but it is often the case that specifiers of software think in terms of units which are too small. Many specifications can be expressed using . data items, but in a way which does not unduly constrain their subsequent refinement down to an implementation. Using the con

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Refinement,ut some particular strategies (such as those given in Chapter 3) we run the risk of going round in circles and wasting much effort getting precisely nowhere. Even when our initial specification is deterministic (and hence specifies a single function rather than a . of functions, any one of which wou

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Sorting, The coverage is by no means complete, in particular there is little attention paid to the creation of clever internal data structures. Our major concern is the detailed application, and a certain amount of customisation., of the general transfinement tactics described earlier.

Parameter

Two Further Examples,ntions to two further examples which illustrate different aspects of algorithm design. These are two important, if unfamiliar, problems which can both be represented pictorially. We could follow them through right down to the level of complete PDL implementations; however, we shall stop at an earlie