View merging, also called view integration, is a key problem in conceptual modeling. Large models are often constructed and accessed by manipulating individual views, but it is important to be able to consolidate a set of views to gain a unified perspective, to understand interactions between views, or to perform various types of end-to-end analysis. View merging is complicated by incompleteness and inconsistency of views. Once views are merged, it is useful to be able to trace the elements of the merged view back to their sources. In this paper, we propose a framework for merging incomplete and inconsistent graph-based views. We introduce a formalism, called poset-annotated graphs, which incorporates a systematic annotation scheme capable of modeling incompleteness and inconsistency as well as providing a built-in mechanism for ownership traceability. We show how structure-preserving maps can capture the relationships between disparate views modeled as poset-annotated graphs, and provide a general algorithm for merging views with arbitrary interconnections. We use the i ∗ modeling language [26] as an example to demonstrate how our approach can be applied to existing graph-based modeling languages, especially in the domain of early Requirements Engineering. 1

This paper presents a specification formalism that combines temporal logic with actions and algebraic modules. This formalism allows to write modular specifications of complex systems and is supported by a tool. We show that we can also exploit the structure of the specification in order to realize modular verifications. It is applied to a telecommunication example.

For succesful information systems development, conceptual data modelling is essential. Nowadays many techniques for conceptual data modelling exist, examples are NIAM, FORM, PSM, many (E)ER variants, IFO, and FDM. In-depth comparisons of concepts of these techniques is very difficult as the mathematical formalisations of these techniques, if existing at all, are very different. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper the use of category theory for this purpose is addressed. Well-known conceptual data modelling concepts are discussed from a category theoretic point of view. Advantages and disadvantages of the approach chosen will be outlined. Keywords: Conceptual Data Modelling, Category Theory, Meta Modelling Classification: 68P99 (AMS-1991), H.1.0. (CR-1991) 1 Introduction It seems an undisputed fact that, opposed to most mature scientific disciplines, the discipline of information systems does not hav...

For successful information systems development, conceptual data modeling is essential. Nowadays many techniques for conceptual data modeling exist. In-depth comparisons of concepts of these techniques are very difficult as the mathematical formalizations of these techniques, if they exist at all, are very different. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper the use of category theory for this purpose is addressed. Well-known conceptual data modeling concepts, such as relationship types, generalization, specialization, collection types, and constraint types, such as the total role constraint and the uniqueness constraint, are discussed from a categorical point of view. An important advantage of this framework is its "configurable semantics". Features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. The addition of these features usually requir...

Structure is important in large specifications for understanding, testing and managing change. Category theory has been explored as framework for providing this structure, and has been successfully used to compose specifications. This work has typically adopted a "correct by construction" approach: components are specified, proved correct and then composed together in such a way to preserve their properties. However, in a large project, it is desirable to be able to mix specification and composition steps such that at any particular moment in the process, we may have established only some of the properties of the components, and some of the composition relations. In this paper we propose adaptations to the categorical framework in order to manage evolving specifications. We demonstrate the utility of the framework on the analysis of a part of a software change request for the Space Shuttle.

. We will consider a new tiny, yet powerful, programming language for distributed systems, called DHOP, which has its operational semantics given as algebraic graph rewrite rules in a certain category of labeled graphs. Our approach allows to separate actions which affect several processes from local changes such as variable bindings. We also sketch how to derive an implementation from this specification. 1 Introduction There are already many calculi for programming distributed systems. Roughly, they can be divided into three groups: 1. Fully fledged programming languages (like occam2 [12], POOL [1], and SR [2]) contain a lot of features useful in practical applications. Their semantics is usually given informally. 2. Small languages (like CSP [11], DNP [7], extended typed -calculus [18], and Facile [19]) could be used for programming tasks, although they concentrate on the main ideas. Their semantics is formally defined. 3. Process algebras (like ACP [5], CCS [14], ß-calculus [15], a...

this paper is an alternative to diagram chasing (4). The use of a standard notation for various unique arrows obviates in some cases the need for pictures for the purpose of naming (2). The need for a pictorial overview of the typing (1) is decreased to some extend by a consistent notation, in particular f ; g for composition (so that f : a ! b g: b ! c ) f

We introduce finite-state verification techniques for the π-calculus whose design and correctness are justified coalgebraically. In particular, we formally specify and implement a minimisation algorithm for HD-automata derived from π-calculus agents. The algorithm is a generalisation of the partition refinement algorithm for classical automata and is specified as a coalgebraic construction defined using λ →,Π,Σ, a polymorphic λ-calculus with dependent types. The convergence of the algorithm is proved; moreover, the correspondence of the specification and the implementation is shown. 1

In recent years, formal methods (FMs) have been extensively used for verification and validation (V&V) of dependable distributed protocols. Over our studies in utilizing FMs for V&V, we have observed that a number of protocols providing for distributed and dependable services can often be formulated using a small set of basic functional primitives or their variations. Thus, from the formal viewpoint, the objective of this paper is to introduce techniques, utilizing concepts of category theory, that could effectively identify and reuse basic formal modules in order to simplify formal specification and verification for a spectrum of protocols.

The open calculus of constructions integrates key features of Martin-Löf's type theory, the calculus of constructions, Membership Equational Logic, and Rewriting Logic into a single uniform language. The two key ingredients are dependent function types and conditional rewriting modulo equational theories. We explore the open calculus of constructions as a uniform framework for programming, specification and interactive verification in an equational higher-order style. By having equational logic and rewriting logic as executable sublogics we preserve the advantages of a first-order semantic and logical framework and especially target applications involving symbolic computation and symbolic execution of nondeterministic and concurrent systems.