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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.

This paper describes the logic of the RAISE Specification Language, RSL. It explains the particular logic chosen for RAISE, and motivates this choice as suitable for a wide spectrum language to be used for designs as well as initial specifications, and supporting imperative and concurrent specifications as well as applicative sequential ones. It also describes the logical definition of RSL, its axiomatic semantics, as well as the proof system for carrying out proofs.

der Eberhard-Karls-Universität Tübingen für das Fach Informatik

In the initial semantics approach to algebraic specification, one usually restricts oneself to conditional equations. It is well-known that this restriction does not affect expressiveness, at least if the introduction of auxiliary (hidden) functions is allowed: all the computable data types can be specified using conditional equations and initial algebra semantics [BT82]. However, the situation is quite different concerning the specification without hidden functions. In this case, the completeness for computable data types is lost for the initial specification methods (cf. [Maj79, TWW82, BT87]) as well as for the loose ones (cf. [Ber93, KS98]). Instead of considering these two approaches separately, it is natural to ask how their expressive powers compare to each other. It is already known that the loose specification methods (even allowing full first-order logic) are not more powerful than the initial methods (even using equations only) [Sch97]. In this paper we give the answ...

There are a number of reasons why software construction is an inherently hard process to master. Specification plays a central role here; therefore, better means of specification improve productivity. One way of achieving this may be the use of formal specification languages, which have the advantage of being unambiguous. This thesis proposes and motivates a new formal specification language called AFSL (Almost Formal Specification Language or Another Formal Specification Language). AFSL is not a full-grown tool that can be used productively in the software industry right away. Rather, its development has been a quest for creative ideas that may enhance the applicability of formal specification in the future. This introduction explains what formal specification is and argues why it is useful, discusses the historical background of AFSL, and gives an overview of the rest of the thesis.