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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.

: This paper presents a number of concepts of a mapping between logical systems modelled as institutions, discusses their mutual merits and demerits, and sketches their role in the process of system specification and development. Some simple properties of the resulting categories of institutions are given. 1 Introduction We have to live with a multitude of logical systems used in various approaches to software specification and development. The proliferation of logical systems in the area is not just researchers' fancy, but results from the very practical needs to capture various aspects of software systems and to cater for various programming paradigms. Each of them leads to a different notion of a semantic model capturing the semantic essence of the adopted view of software systems. For instance, standard (many-sorted) algebras [BL70], [GTW78] provide a satisfactory framework for modelling data types where all operations always yield well-defined results. However, if general recursi...

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. Various formalizations of the concept of "refinement step" as used in the formal development of programs from algebraic specifications are presented and compared. 1 Introduction Algebraic specification aims to provide a formal basis to support the systematic development of correct programs from specifications by means of verified refinement steps. Obviously, a central piece of the puzzle is how best to formalize concepts like "specification", "program" and "refinement step". Answers are required that are simple, elegant and general and which enjoy useful properties, while at the same time taking proper account of the needs of practice. Here I will concentrate on the last of these concepts, but first I need to deal with the other two. For "program", I take the usual approach of algebraic specification whereby 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 commens...

: This is a technical paper stating and proving completeness and cocompleteness results for various categories of institutions. 1 Introduction This is a technical companion report to [Tar96], where an overview of various notions of a mapping between institutions is given and some structural properties of the resulting categories of institutions are indicated. The main goal of the current report is to provide technical statements of these results and to prove them in sufficient detail. Some of the results given here have been only hinted at in [Tar96], some of them are repeated from [Tar96], and some are known from the earlier literature. For the sake of completeness of this report we recall all the formal definitions which underly the results --- we refrain however from giving any motivations and informal analysis of the role of the notions introduced and results proved. We will also sketch the proofs of known results, since they provide a necessary background for the proofs which hav...

Abstract. We extend CASL architectural specifications with a simple refinement language that allows the formalization of developments as refinement trees. The essence of the extension is to allow refinements of unit specifications in CASL architectural specifications. 1 Introduction The standard development paradigm of algebraic specification [1] postulates thatthe development begins with a formal requirement specification SP 0 (extractedfrom a software project's informal requirements) that fixes only expected properties but ideally says nothing about implementation issues; this is to be followedby a number of refinement steps that fix more and more details of the design, until a specification SP n is obtained that is detailed enough that its conversioninto a program

On the first hand, this report studies the class of Greedy Algorithms in order to find an as systematic as possible strategy that could be applied to the specification of some problems to lead to a correct program solving that problem. On the other hand, the standard formalisms underlying the Greedy Algorithms (matroid, greedoid and matroid embedding) which are dependent on the particular type set are generalized to a formalism independent of any data type based on an algebraic specification setting.

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Specifications 11h45--12h15 Hans-Jorg Kreowski and Till Mossakowski: LARGE Based Algebras and Horn Clause Theories 12h15--12h45 Hartmut Ehrig, Rosa Jimenez and Fernando Orejas: Compositionality Results for Different Types of Parameterization and Parameter Passing in Specification Languages 12h45--13h05 Hubert Baumeister: Parameter Passing in the Typed -Calculus Approach to Parameterized Specifications 13h05 Lunch 15h00--15h20 Horst Reichel: First--order Specification of Infinite Objects 15h20--15h40 Martin Grosse-Rhode and Uwe Wolter: 2-Categorical Specification of Partial Algebras 15h40--16h00 Michal Walicki: Multialgebras and Computations: Two Algebraic Semantics of Non-determinism 16h00--16h20 Brian McConnel and John V. Tucker: Direct limits of Algebras and the Parameterization of Synchronous Concurrent Algorithms 16h20--16h50 Coffee break 16h50--17h10 Stefan Conrad, Rudolf Herzig: On Transforming Object Specifications into a Certification Calculus 17h10--17h30 Wolfgang Reif: Reus...