In this work, we investigate various specification languages and their relation to Casl, the recently developed Common Algebraic Specification Language. In particular, we consider the languages Larch, OBJ3, CafeOBJ, ACT ONE, ASF, and HEP-theories, as well as various sublanguages of Casl that more or less directly correspond to these. All these languages are translated to an appropriate sublanguage of Casl. 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 one hand translations of any of the abovementioned specification languages to an appropriate sublanguage of Casl. This allows us to take libraries and case studies that have been developed for other languages and re-use them in Casl. On the other hand, we set up institution repre...

The development of programs in modern functional languages such as Haskell calls for a wide-spectrum specification formalism that supports the type system of such languages, in particular higher order types, type constructors, and parametric polymorphism, and contains a functional language as an executable subset in order to facilitate rapid prototyping. We lay out the design of HasCasl, a higher order extension of the algebraic specification language Casl that is geared towards precisely this purpose. Its semantics is tuned to allow program development by specification refinement, while at the same time staying close to the set-theoretic semantics of first order Casl. The number of primitive concepts in the logic has been kept as small as possible; we demonstrate how various extensions to the logic, in particular general recursion, can be formulated within the language itself.

CASL, the common algebraic specification language, has been developed as a language that subsumes many previous algebraic specification frameworks and also provides tool interoperability. CASL is a complex language with a complete formal semantics. It is therefore a challenge to build good tools for CASL. In this work, we present and discuss the Bremen HOL-CASL system, which provides parsing, static checking, conversion to LaTeX and theorem proving for CASL specifications. To make tool construction manageable, we have followed some guidelines: re-use of existing tools, interoperability of tools developed at different sites, and construction of generic tools that can be used for several languages. We describe the structure of and the experiences with our tool and discuss how the guidelines work in practice.

Casl is an expressive language for the 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.

Monads have been recognized by Moggi as an elegant device for dealing with stateful computation in functional programming languages. It is thus natural

We provide a semantic basis for heterogeneous specifications that not only involve different logics, but also different kinds of translations between these. We show that Grothendieck institutions based on spans of (co)morphisms can serve as a unifying framework providing a simple but powerful semantics for heterogeneous specification.

Abstract. We present a semantics for architectural specifications in Casl, including an extended static analysis compatible with modeltheoretic 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 has amalgamation, 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.

Grammar 33 A.1 Basic Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 A.2 Basic Specifications with Subsorts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 A.3 Structured Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 A.4 Architectural Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 A.5 Specification Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 B Specification of the Case Study 37 1

As the first of two methodological devices aimed at increasing the trust in the `correctness' of a specification, we develop a calculus for proving consistency of Casl specifications. It turns out to be possible to delegate large parts of the proof load to syntactical criteria by structuring consistency proofs along the given specification structure, so that only in rather few remaining focus points, actual theorem proving is required. The practical usability of the resulting calculus is demonstrated by extensive examples taken from the Casl library of basic data types.

Multi-formalism specifications are essential for the modelling of complex systems including different aspects such as data or concurrency. We advocate a formalism which combines the CCS process algebra with the CASL algebraic specification language. Formal foundations of this combination are presented following two steps, the syntax and the semantics. Our proposal is illustrated with a real size case study: an access control system to a set of buildings. With this concrete example, we aim at showing how our formalism proposal could be used to specify a comprehensive application.