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This paper is concerned primarily with (1) the procedure by which process-oriented specifications are obtained from goal-oriented requirement specifications and (2) computer-based tools for their construction. It first determines some attributes of a suitable process-oriented specification language, then examines the reasons why specifications would still be difficult to write in such a language. The key to overcoming these difficulties seems to be the careful introduction of informality based on partial, rather than complete, descriptions and the use of a computer-based tool that uses context extensively to complete these descriptions during the process of constructing a well-formed specification. Some results obtained by a running prototype of such a computer-based tool on a few informal example specifications are presented and, finally, some of the techniques used by this phototype system are discussed.

The concept of Open GIS depends on precise definitions of data, operations and interfaces. This paper argues for the use of functional programming languages as specification and prototyping tools for Open GIS components. It shows how functional programming languages fulfill the key requirements for formal specification languages and allow for rapid prototyping in addition. So far, it has never been possible to integrate specification and prototyping in a single, easy to use environment. Most existing specification methods lack appropriate tools for checking and prototyping, while existing tools lack either sound semantics or usability or both. The paper discusses the role of specifications in GIS, requirements for specification languages, and a survey of algebraic specifications as well as of functional languages. It then describes how functional languages can be used for writing and executing algebraic specifications. A brief example of a GIS data type specification in a functional la...

Data Types and Software Validation ," Communications of the ACM, Vol. 21, No. 12, 1978, pp. 1048-1064.

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What is the computational notion of "implementation"? It is not individuation, instantiation, reduction, or supervenience. It is, I suggest, semantic interpretation. This document is Technical Report 97-15 (Buffalo: SUNY Buffalo Department of Computer Science) and Technical Report 97-5 (Buffalo: SUNY Buffalo Center for Cognitive Science). 1 INTRODUCTION Consider the relationships among algorithms, computer programs, and the computers that execute them. An algorithm is (roughly) a procedure for computing a function (for more details, see Soare 1996; Rapaport, forthcoming). A program is a more specific and detailed textual expression of an algorithm, expressed in a programming language. Often, it is said that the program "implements" the algorithm. A computer process is an algorithm being executed (see Rapaport 1988, 1995; Smith 1997). It is a physical device (a computer) behaving in a certain way ; the way is described (or specified) by the program, and the physical device running the ...

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