Common Algebraic Specification Language Research Articles

Levels of presenting ontologies, languages, mathematical models, and ontology web-server project in Web 2.0

This paper presents an ontology web-server project in Web 2.0 that allows the collaborative development of ontologies. The levels of presenting ontologies and mathematical models underlying these presentations are discussed. The CASL language (Common Algebraic Specification Language) is reviewed.

Implementing Local Intervals in CASL

This paper defines the basis for the implementation in CASL (Common Algebraic Specification Language) of an interval library such that intervals behave as real numbers endowed with an error information. To achieve that, we redefine the notion of interval local set defined in [R.H.N. Santiago. Interval local equality toward a model for real type. In Proceedings of the IV Workshop on Formal Methods, pages 54–59, Rio de Janeiro, RJ, 2001. Sociedade Brasileira de Computação] in such a way that it can be implemented in the underlying logic of CASL. With these results, it is possible to manipulate intervals in CASL, as if they were real numbers, with equational reasoning, and get an error estimation on the obtained results for free (from the width of the resulting interval). The paper describes the CASL definition of the interval library and presents a case study on a simple example requiring handling data with “tolerance” margin.

CSP-CASL—A new integration of process algebra and algebraic specification

C SP–C ASL integrates the process algebra C SP [T. Hoare, Communicating Sequential Processes, Prentice-Hall, Englewood cliffs, NJ, 1985; A.W. Roscoe, The Theory and Practice of Concurrency, Prentice-Hall, Englewood cliffs, NJ, 1998] with the algebraic specification language C ASL [P.D. Mosses (Ed.), C ASL Reference Manual, Lecture Notes in Computer Science, Vol. 2960, Springer, Berlin, 2004; E. Astesiano, M. Bidoit, B. Krieg-Brückner, H. Kirchner, P.D. Mosses, D. Sannella, A. Tarlecki, C ASL—the common algebraic specification language, Theoret. Comput. Sci. 286 (2002) 153–196]. Its novel aspects include the combination of denotational semantics in the process part and, in particular, loose semantics for the data types covering both concepts of partiality and sub-sorting. Technically, this integration involves the development of a new so-called data-logic formulated as an institution. This data-logic serves as a link between the institution underlying C ASL and the alphabet of communications necessary for the C SP semantics. Besides being generic in the various denotational C SP semantics, this construction leads also to an appropriate notion of refinement with clear relations to both data refinement in C ASL and process refinement in C SP.

A formally grounded software specification method

One of the goals of software engineering is to provide what is necessary to write relevant, legible, useful descriptions of the systems to be developed, which will be the basis of successful developments. This goal was addressed both from informal approaches (providing in particular visual notations) and formal ones (providing a formal sound semantic basis). Informal approaches are often driven by a software development method, and, while formal approaches sometimes provide a user method, it is usually aimed at helping to use the proposed formalism when writing a specification. Our goal here is to provide a companion method that helps the user to understand the system to be developed, and to write the corresponding formal specifications. We also aim at supporting visual presentations of formal specifications, so as to “make the best of both formal and informal worlds”. We developed this method for the (logical-algebraic) specification languages CASL (Common Algebraic Specification Language, developed within the joint initiative CoFI) and for an extension for dynamic systems C asl-L tl, and we believe it is general enough to be adapted to other paradigms. Another challenge is that a method that is too general does not encompass the different kinds of systems to be studied, while too many different specialized methods result in partial views that may be difficult to integrate in a single global one. We deal with this issue by providing a limited number of instances of our method, fitted for three different kinds of software items, while keeping a common “meta”-structure and way of thinking. More precisely, we consider here that a software item may be a simple dynamic system, a structured dynamic system, or a data structure, and we show here how to support property-oriented (axiomatic) specifications. We are thus providing support for the “building-bricks” tasks of specifying software artifacts that in our experience are needed for the development process. Our approach is illustrated with a lift case study.

Amalgamation in the semantics of C ASL

We present a semantics for architectural specifications in the Common Algebraic Specification Language ( Casl), including an extended static analysis compatible with model-theoretic requirements. The main obstacle here is the lack of amalgamation for Casl models. To circumvent this problem, we extend the Casl logic by introducing enriched signatures, where subsort embeddings form a category rather than just a preorder. The extended model functor satisfies the amalgamation property as well as its converse, which makes it possible to express the amalgamability conditions in the semantic rules in static terms. Using these concepts, we develop the semantics at various levels in an institution-independent fashion. Moreover, amalgamation for enriched Casl means that a variety of results for institutions with amalgamation, such as computation of normal forms and theorem proving for structured specifications, can now be used for Casl.

A Tool Support for Reusing ELAN Rule-Based Components

The adaptation of software components developed for a specific application in order to generate reusable components often includes some kind of generalization. This generalization may be carried out, for instance, by the renaming of some identifiers or by its parameterization. In our work, we are specially interested in the generalization by parameterization of algebraic specification components. Generalization and some other transformations on algebraic specifications are being integrated in the FERUS tool. This tool was initially developed for the Common Algebraic Specification Language, called CASL, and we show in the paper its adaptation to the new version of the rule-based programming language ELAN.

Architectural Specifications in CASL

Abstract. One of the most novel features of C ASL , the Common Algebraic Specification Language, is the provision of so-called architectural specifications for describing the modular structure of software systems. A brief discussion of refinement of C ASL specifications provides the setting for a presentation of the rationale behind architectural specifications. This is followed by some details of the features provided in C ASL for architectural specifications, hints concerning their semantics, and simple results justifying their usefulness in the development process.

Relating CASL with other specification languages: the institution level

In this work, we investigate various specification languages and their relation to C ASL, the recently developed Common Algebraic Specification Language. In particular, we consider the languages Larch, OBJ3 and functional CafeOBJ, ACT ONE, ASF, and HEP-theories, as well as various sublanguages of C ASL. All these languages are translated to an appropriate sublanguage of C ASL. The translation mainly concerns the level of specification in-the-small: the logics underlying the languages are formalized as institutions, and representations among the institutions are developed. However, it is also considered how these translations interact with specification in-the-large. Thus, we obtain, on the one hand, translations of any of the above-mentioned specification languages to an appropriate sublanguage of C ASL. This allows us to take libraries and case studies that have been developed for other languages and re-use them in C ASL. On the other hand, we set up institution representations going from the C ASL institution (and some of its subinstitutions) to simpler subinstitutions. Given a theorem proving tool for such a simpler subinstitution, with the help of a representation, it can also be used for a more complex institution. Thus, first-order theorem provers and conditional term rewriting tools become usable for C ASL.

CASL: the Common Algebraic Specification Language

The Common Algebraic Specification Language (C ASL) is an expressive language for the formal specification of functional requirements and modular design of software. It has been designed by C OFI, 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. C ASL should facilitate interoperability of many existing algebraic prototyping and verification tools. This paper gives an overview of the C ASL design. The major issues that had to be resolved in the design process are indicated, and all the main concepts and constructs of C ASL are briefly explained and illustrated — the reader is referred to the C ASL Language Summary for further details. Some familiarity with the fundamental concepts of algebraic specification would be advantageous.