On two different Characterizations of Bisimulation

Theoretical Computer …, 2002

Casl is an expressive language for the formal specification of functional requirements and modular design of software. It has been designed by CoFI, the international Common Framework Initiative for algebraic specification and development. It is based on a critical selection of features that have already been explored in various contexts, including subsorts, partial functions, first-order logic, and structured and architectural specifications. Casl should facilitate interoperability of many existing algebraic prototyping and verification tools. This paper gives an overview of the Casl design. The major issues that had to be resolved in the design process are indicated, and all the main concepts and constructs of Casl are briefly explained and illustrated-the reader is referred to the Casl Language Summary for further details. Some familiarity with the fundamental concepts of algebraic specification would be advantageous.

TAPSOFT'97: Theory and Practice of Software …, 1997

An open collaborative e ort has been initiated: to design a common framework for algebraic speci cation and development of software. The rationale behind this initiative is that the lack of such a common framework greatly hinders the dissemination and application of research results in algebraic speci cation. In particular, the proliferation of speci cation languages, some di ering in only quite minor ways from each other, is a considerable obstacle for the use of algebraic methods in industrial contexts, making it di cult to exploit standard examples, case studies and training material. A common framework with widespread acceptance throughout the research community is urgently needed. The aim is to base the common framework as much as possible on a critical selection of features that have already been explored in various contexts. The common framework will provide a family of speci cation languages at di erent levels: a central, reasonably expressive language, called CASL, for specifying (requirements, design, and architecture of) conventional software; restrictions of CASL to simpler languages, for use primarily in connection with prototyping and veri cation tools; and extensions of CASL, oriented towards particular programming paradigms, such as reactive systems and object-based systems. It should also be possible to embed many existing algebraic speci cation languages in members of the CASL family. A tentative design for CASL has already been proposed. Task groups are studying its formal semantics, tool support, methodology, and other aspects, in preparation for the nalization of the design.

BULLETIN-EUROPEAN ASSOCIATION FOR …, 1996

Casl, the Common Algebraic Specification Language, has been designed by CoFI, the Common Framework Initiative for algebraic specification and development. It is an expressive language for specifying requirements and design for conventional software. It is algebraic in the sense that models of Casl specifications are algebras; the axioms can be arbitrary first-order formulae.

2001

The Common Framework Initiative ( ) is an open international collaboration which aims to provide a common framework for algebraic specification and development of software. The central element of the Common Framework is a specification language called Casl for formal specification of functional requirements and modular software design which subsumes many previous algebraic specification languages. This paper is a brief summary of progress on CoFI during the period 1998-2001, when CoFI received funding from the European Commission as a Working Group under the Esprit programme.

Abstract The specification of all aspects of a programming language requires adequate formal models and tool support. Montages specifications combine graphical and textual elements to yield language descriptions similar in structure, length, and complexity to those in common language manuals, but with a formal semantics. A broad range of people involved in programming language design and use may find it convenient to use Montages in combination with the tool GEM–MEX.

CAV, 2001

µCRL is a language for specifying and verifying distributed systems in an algebraic fashion. It targets the specification of system behaviour in a process-algebraic style and of data elements in the form of abstract data types. The µCRL toolset supports the analysis and manipulation of µCRL specifications. A µCRL specification can be automatically transformed into a linear process operator (LPO). All other tools in the µCRL toolset use LPOs as their starting point. The simulator allows the interactive simulation of an LPO. There are a number of tools that allow optimisations on the level of LPOs. The instantiator generates a labelled transition system (LTS) from an LPO (under the condition that it is finite-state), and the resulting LTS can be visualised, analysed and minimised.

Formal Aspects of Computing, 1997

The main ideas underlying work on the model-theoretic foundations of algebraic specification and formal program development are presented in an informal way. An attempt is made to offer an overall view, rather than new results, and to focus on the basic motivation behind the technicalities presented elsewhere.

ACM Computing Surveys, 1999

This note gives our personal perspective on the state of foundations of software specification and development including applications to the formal development of reliable complex software systems. We regard this area of research as straddling the borderline between theory and practice. It has connections with work on the design and semantics of software systems and programming languages, on formal methods for system verification (various program logics in particular), and relies heavily on some basic concepts of mathematical logic, universal algebra and category theory, while being directly inspired by and potentially applicable in practice. In this note we sum up our experiences so far, hint at the need for further work in certain areas, and speculate a bit about the directions in which we expect to go in the future. The roots of our work in this area are in the theory of algebraic specification. The most fundamental assumption underlying this theory is that programs are modelled as many-sorted algebras consisting of a collection of sets of data values together with functions over those sets. This level of abstraction is commensurate with the view that the correctness of the input/output behaviour of a program takes precedence over all its other properties. Another common element is that specifications of programs consist mainly of logical axioms, usually in a logical system in which equality has a prominent role, describing the properties that the functions are required to satisfy. This property-oriented approach is in contrast to so-called model-oriented specifications which consist of a simple realization of the required behaviour. A wide variety of different approaches to algebraic specification take these two principles as their starting point. Research on algebraic specification has been devoted mainly to the search for an adequate account of the fundamental concepts and basic processes involved in the

Lecture Notes in Computer Science, 1983

A kernel specification language called ASL is presented. ASL comprises five fundamental but powerful specificationbuilding operations and has a simple semantics. Behavioural abstraction with respect to a set of observable sorts san be expressed, and (recurstve) parameterisad specifications can be defined using a more powerful and more expressive parameterisation mechanism than usual. A simple notion of implementation permitting vertical and horizontal composition (i.e. it is transitive and monotonic) is adopted and compared with previous more elaborate notions. A collection of identities is given which san provide a foundation for the development of programs by transformation.

Science of Computer Programming, 1989

This paper relates an experiment in writing an algebraic specification of a rather complex example, namely a subset of the UNIX' file system. The PLUSS specification language, which is used for this experiment, provides a set of linguistic features which allow the modularization of such specifications and the definition of a flexible and convenient syntax for expressions and axioms (such as mixtix operators, overloading, coercions). This experiment was a way for evaluating the adequacy of these features to several criteria: mainly legibility and understandability, but also reusability of specifications. The paper presents the specification and discusses it with respect to these important points. * This work is partially supported by ESPRIT project No. 432 METEOR and CNRS GRECO de Programmation. ' UNIX is a trademark of Bell Laboratories.