Information Integration is one of the core problems in cooperative information systems. We argue that two critical factors for the design and maintenance of applications requiring Information Integration are conceptual modeling of the domain, and reasoning support over the conceptual representation. In particular, we present a general architecture for Information Integration that explicitly includes a conceptual representation of the application. We illustrate how the architecture can express several integration settings and existing systems. We provide various arguments in favor of the conceptual level in the architecture and of automated reasoning over the conceptual representation. Finally, we present a specific proposal of an integration system which realizes the general architecture and is equipped with decidable reasoning procedures. 1.

Whilst it is a common task in systems integration to have to transform between different semantic data models, such inter-model transformations are often specified in an ad hoc manner. Further, they are usually based on transforming all data into one common data model, which may not contain suitable data constructs to model directly all of the constructs of the data models being integrated. Our approach is to define each of the data models to be integrated in terms of a more `elemental', low-level data model-- a hypergraph-based one. We show how these definitions can be used to automatically derive schema transformation operators for the higher-level data models. These higher-level transformations can be used to perform inter-model transformations, and in turn allow data and queries to be automatically translated from one model to another. Finally, we show how to use the hypergraph data model in order to define inter-model links, and hence allow queries which span more than one model.

The integration of information from multiple databases has been an enduring subject of research for almost 20 years, and many di erent solutions have been attempted or proposed. Missing from this research has been a uniform framework. Usually, each solution develops its own ad-hoc framework, designed to address the particular aspects of the problem that are being attacked and the particular methodology that is being used. To address this situation, in this paper we de ne a formal model for multidatabases, which we call Multiplex. Multiplex is a simple extension of the relational model, which may serve as a uniform abstraction for many previous ad-hoc solutions. Multiplex is based on formal assumptions of integrability, which distinguish between scheme and instance reconcilability among independent databases. Multiplex supports database heterogeneity, and it provides several degrees of freedom that allow it to model actual situations encountered in multidatabase applications. In addition, in situations in which a single answer is not obtainable (either because the global query is not answerable, or there are multiple candidate answers), Multiplex de nes approximative answers. Finally, Multiplex provides a practical platform for implementation. A prototype of such an implementation is described brie y.

In recent years there has been a growing interest in accessing, relating, and combining data from multiple sources. Indeed, Information Integration is one of the core problems in distributed databases, cooperative information systems, and data warehousing, which are key areas in the software development industry. Two critical factors for the design and maintenance of applications requiring Information Integration are conceptual modeling of the domain, and reasoning support over the conceptual representation. We demonstrate that Knowledge Representation and Reasoning techniques can play an important role for both of these factors, by proposing a Description Logic based framework for Information Integration. We show that the development of successful Information Integration solutions requires not only to resort to very expressive Description Logics, but also to significantly extend them. We present a novel approach to conceptual modeling for Information Integration, which allows for suitably modeling the global concepts of the application, the individual information sources, and the constraints among different sources. Moreover, we devise inference procedures for the fundamental reasoning services, namely relation and concept subsumption, and query containment. Finally, we present a methodological framework for Information Integration, which can be applied in several contexts, and highlights the role of reasoning services within the design process. 1

This paper addresses several issues related to the use of conceptual modeling to support serviceoriented, advanced information systems. It shows how conceptual modeling of information resources can be used to integrate information obtained from multiple data sources, including both internal and external data. The notion of an intelligent thesaurus is presented and a meta-model of the thesaurus is developed. It is then used to create a three-layer architecture consisting of the actual data source schemas, a wrapped object-oriented abstraction of the schemas expressed in terms of the thesaurus primitives, and an integrated version which serves as the federation schema. The sharing of information among constituents is also addressed, and a special export schema - the export data/knowledge/task schema - is proposed that ties together the objects, their constraints, and their usage rules. Knowledge sharing among constituents during cooperative query processing is accomplished using data/knowledge packets. Key Words: Intelligent Thesaurus, Knowledge Sharing, Ontology 1