ion of Representation for Interoperation David A. Maluf and Gio Wiederhold Department of Computer Science Stanford University Stanford, CA 94305 Abstract. When combining data from distinct sources, there is a need to share meta-data and other knowledge about various source domains. Due to semantic inconsistencies, problems arise when combining knowledge across domains and the knowledge is simply merged. Also, knowledge that is irrelevant to the task of interoperation will be included, making the result unnecessarily complex. An algebra over ontologies has been proposed to support disciplined manipulation of domain knowledge resources. However, if one tries to interoperate directly with the knowledge bases, semantic problems arise due to heterogeneity of representations. This heterogeneity problem can be eliminated by using an intermediate model that controls the knowledge translation from a source knowledge base. The intermediate model we have developed is based on the concept of abst...

. Applying object-oriented technology to systems development is widely recognized as improving productivity and reducing system maintenance costs. At the same time, relational technology has gained leverage in most businesses. There exist already several proposals to combine object-oriented programming with relational database systems. Yet, existing approaches do not support necessary combinations of object-oriented and relational technology in concert, like reengineering of existing relational data in an object-oriented way, and adding persistence to existing object-oriented applications. COMan (Complex Object Manager) has been developed to fill this gap. The kernel architecture of COMan is based on a set of tables, called meta database, which supports the flexible mapping from a set of object classes to a relational schema and vice versa. Thus, COMan provides necessary infrastructure technology for business reengineering seeking important leverage of legacy databases. Keywords. Repo...

. In the literature there are several proposals to map entityrelationship schemas onto object-oriented schemas, but they only treat relationship sets naively or restrict them to binary relationship sets. We follow a different approach in the treatment of relationship sets. Our goal is to let the designer specify relationships of any arity and then to employ semantic constraints to decompose relationships into smaller fragments. The semantic constraints in use are functional constraints, which are defined in the object-oriented framework. The decomposition process guided by functional constraints is similar to the decomposition process in the relational approach with functional dependencies, but it takes advantage of the features provided by the object-oriented data model. In object-oriented schemas it is possible to enforce a certain kind of functional constraints automatically, namely unary functional constraints. 1 Introduction The Entity-Relationship approach (ER approach) to model...

The system Queer is a prototype of an information system design tool which directly supports an extended Entity-Relationship model on its front-end and uses a semantically well-founded query and manipulation language based on an EntityRelationship calculus. The system basically consists of a set of compilers written in Prolog which translate data specifications, schema definitions, queries, integrity constraints, and data-manipulation statements into Prolog programs. All features mentioned are implemented in form and extent as described here. Keywords: Conceptual Modelling; Entity Relationship Model; Object-Oriented Modelling; Logic Programming; Prototyping. 1 Introduction Conceptual modelling plays the central role among the different steps in database design. The result of the modelling process is a comprehensive and first formal description of the part of the world to be modelled. Usually, this step is done by employing a semantic data model like TAXIS [35], SDM [17], IRIS [32], o...

Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.5.4 Special Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.6 Semantics of Programming Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.6.1 Semantics of Ada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.6.2 Action Semantics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.7 Specification Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.7.1 Early Algebraic Specification Languages . . . . . . . . . . . . . . . . . . . . . . . . 53 4.7.2 Recent Algebraic Specification Languages . . . . . . . . . . . . . . . . . . . . . . . 55 4.7.3 The Common Framework Initiative. . . . . . . . . . . . . . . . . . . . . . . . . . . 56 5 Methodology 57 5.1 Development Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5.1.1 Applica...

Techniques for the development of reliable information systems on the basis of their formal specification are the main concern in our project. Our work focuses on the specification language TROLL light which allows to describe the part of the world to be modeled as a community of concurrently existing and communicating objects. Our specification language comes along with an integrated, open development environment. The task of this environment is to give support for the creation of correct information systems. Two important ingredients of the environment to be described here in more detail are the animator and the proof support system.