LOTOS(ID:1493/lot003)Specification language based on temporal orderingSpecification language based on temporal ordering. According to Bruns 1991, Data portion was based on ACT ONE Related languages
References: in Formal Description Techniques, Ken Turner (Ed), North-Holland 1989 view details in Proc. of the 2nd FORmal TEchniques Symposium (Vancouver, December 1989). view details in Proc. of the 2nd FORmal TEchniques Symposium (Vancouver, December 1989). view details in Proc. of the 2nd FORmal TEchniques Symposium (Vancouver, December 1989). view details External link: Online copy in Proc. of the 2nd FORmal TEchniques Symposium (Vancouver, December 1989). view details The present volume is an annotated bibliography which attempts to provide an up-to-date overview of past and present work on algebraic specification. No attempt is made to provide a coherent introduction to the topic for beginners the intention is rather to provide a guide to the current literature for researchers in algebraic specification and neighbouring fields. Some indications of how the different approaches are related are included. ps Extract: Extended ML Extended ML The long-term goal of work on Extended ML is to provide a practical framework for formal development of Standard ML programs together with an integrated suite of computer-based specification and development support tools and complete mathematical foundations to substantiate claims of correctness. The complete formal definition of the Extended ML language [533] constitutes an important milestone in this programme, necessary to provide a basis for further research on foundations and tools. One of the key issues that had to be resolved was the design of a logic suitable for describing properties of Standard ML programs, taking into account features like recursive type and function definitions, exceptions, polymorphism, and non-termination. A number of errors in the Standard ML semantics [679] have been discovered in the course of this work [526]. Work has begun on rules for proving theorems about EML specifications, to be used in verifying correctness conditions that arise in the course of formal development. Research has so far concentrated on equality reasoning [530] and quantifier rules. The length and requisite formality of the definition of Extended ML renders it rather difficult to penetrate. Accordingly, [532, 534] provides an informal overview of the definition, explaining most of the main issues involved and justifying some of the choices taken. Extract: LOTOS and PSF LOTOS and PSF are two formalisms following the approach of separate specification of data by choosing a process calculus as the formalism for concurrency. The differences between them are in the formalism for the algebraic specification part (ACT ONE [311] for LOTOS and ASF [64] for PSF) and in the combinators of the chosen process calculus (inspired by those of CCS for LOTOS and by ACP for PSF). PSF (see [657]) is the process specification formalism developed by Mauw and Veltink as a basis for a set of tools to support the process algebra of Bergstra, Klop et al' (see e.g. [65, 48]). The basic specification formalism is equational logic with total algebras. The theory and language of ASF is adopted for handling modular and parameterized specifications. LOTOS has probably been the first internationally known algebraic specification formalism for concurrency (see [187, 143]); most importantly, it is an official ISO language specification for open distributed systems, a qualification that alone would rank it high in an ideal value scale of possible important applications. LOTOS uses ACT ONE ( [311]) for the ADT specifications and a process description formalism based on an extension of CCS with several derived combinators (e.g. input/output of structured values, sequential composition with possible value passing, enabling/disabling operators). The basic specification formalism (equational logic with total algebras) is the same as in PSF and also the bisimulation semantics for processes. All these years, LOTOS has been used in several practical applications. Moreover, a toolset for helping to write correct LOTOS specifications has been developed (see e.g. the ESPRIT project LOTOSPHERE [911]). Recently a revised version of LOTOS (E-LOTOS, for Enhanced LOTOS) is under way, see [620], taking into account the needs raised during its application in industry. Extract: LOTOS LOTOS has probably been the first internationally known algebraic specification formalism for concurrency. LOTOS uses ACT ONE for the algebraic specification of data and a description formalism based on an extension of CCS for processes. A toolset (see e.g. the ESPRIT project LOTOSPHERE) has been developed and a revised version of LOTOS (Enhanced LOTOS) is under way Extract: Reusability The demand for reusability originates from economic considerations and attempts towards standardization. Rather than always starting from scratch, the use of existing components is cheaper and also less error-prone. A central problem for the identification and the correct use of reusable components is the abstract description of such components. A formal specification is the only form of description that can serve as a basis for a correctness proof; it can be processed automatically and it establishes a degree of confidence in the functionality of the component that is particularly important if a component has to be modified before being reused. Goguen [404] proposes the algebraic specification language OBJ as well-suited for the design of reusable software systems. A component's interface is specified as an abstract data type and may be parameterized by other components. Combination of components is possible by instantiation using appropriate fitting morphisms. A similar approach is used in Extended ML [836], [848]. In ACT TWO [315] components are modules, which consist of two interface specifications, i.e. an export specification and an import specification, and a body specification which implements the export specification in terms of the import specification. Similarly, in LARCH [445], a component consists of a pair, an "abstract" interface specification and an implementation. Here the implementation is written in a conventional programming language. A similar distinction between a requirement and a design specification is made in PAnndA-S, the language of the PROSPECTRA project [138], based on the notion of visible and private interface in Ada. Ada bodies are generated semi-automatically by transformation. In the approach of [655] a component consists of four parts at four different levels of abstraction: a requirement specification, a design specification, a source program and object code. Components are written in a so-called wide spectrum language which provides facilities for system design and software development at many levels of abstraction. Matsumoto uses Ada, which has as a consequence that the requirement specification is merely an informal description. CIP-L [54] and COLD [341] are two languages which include algebraic specifications as well as predicative and imperative language styles in one coherent framework and therefore are better suited for such an approach. In the object-oriented approach of [675] a reusable component is represented by a graph of object-oriented programs, each node of which stands for one level of abstraction in the description of the software. In the approach of the ESPRIT-project DRAGON [945], a reusable component consists of a tree of algebraic specifications, where similarly to [675], each node of the tree is an instance of a certain level of an abstraction of the program with the root being the most "abstract" formal specification and the leaves representing the "concrete" implementations. A methodology for reusing components is described in [947]. in Proc. of the 2nd FORmal TEchniques Symposium (Vancouver, December 1989). view details Resources
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