Integrity constraints are rules which should guarantee the integrity of a database. Provided that an adequate mechanism to express them is available, the following question arises: is there any way to populate a database which satisfies the constraints supplied by a database designer? i.e., does the database schema, including constraints, admit at least a non--empty model? This work gives an answer to the above question in a complex object database environment, providing a theoretical framework including the following ingredients: two alternative formalisms, able to express a relevant set of state integrity constraints with a declarative style; two specialized reasoners, based on the tableaux calculus, able to check the consistency of complex objects database schemata expressed with the two formalisms. The proposed formalisms share a common kernel, which supports complex objects and object identifiers, and allow the expression of acyclic descriptions of: classes, nested relati...

. ODB-Tools is a integrated environment for the object oriented database (OODB) validation, preserving taxonomy coherence and performing taxonomic inferences, and semantic query optimization. Semantic query optimization uses problem-specific knowledge (e.g. integrity constraints) for transforming a query into an equivalent one (i.e. with the same answer set) that may be answered more efficiently. The approach of the tool is based on two fundamental ingredients. The first one is the OCDL description logics proposed as a common formalism to express class descriptions, a relevant set of integrity constraints rules (IC rules) and queries. The second one are Description Logics inference techniques, exploited to evaluate the logical implications expressed by IC rules and thus to produce the semantic expansion of a given query. The optimizer tentatively applies all the possible transformations and delays the choice of beneficial transformation till the end. ODB-Tools is a ODMG 93 [1] compli...

SI-Designer (Source Integrator Designer) is a designer support tool for semi;automatic integration of heterogeneous sources schemata (relational, object and semi;structured sources); it has been implemented within the MOMIS project and it carries out integration following a semantic approach which uses intelligent Description Logics-based techniques, clustering techniques and an extended ODMG-ODL language, ODL I 3, to represent schemata, extracted, integrated information. Starting from the sources ’ ODL I 3 descriptions (local schemata) SI-Designer supports the designer in the creation of an integrated view of all the sources (global schema) which is expressed in the same ODL I 3 language. We propose SI-Designer as a tool to build virtual catalogs in the E-Commerce environment.

Abstract. Providing an integrated access to multiple heterogeneous sources is a challenging issue in global information systems for cooperation and interoperability. In the past, companies have equipped themselves with data storing systems building up informative systems containing data that are related one another, but which are often redundant, not homogeneous and not always semantically consistent. Moreover, to meet the requirements of global, Internet-based information systems, it is important that the tools developed for supporting these activities are semi-automatic and scalable as much as possible. To face the issues related to scalability in the large-scale, in this paper we propose the exploitation of mobile agents in the information integration area, and, in particular, their integration in the MOMIS infrastructure. MOMIS (Mediator EnvirOnment for Multiple Information Sources) is a system that has been conceived as a pool of tools to provide an integrated access to heterogeneous information stored in traditional databases (for example relational, object oriented databases) or in file systems, as well as in semi-structured data sources (XML-file). This proposal has been implemented within the MIKS (Mediator agent for Integration of Knowledge Sources) system and it is completely described in this paper. 1

Developing intelligent tools for the integration of information extracted from multiple heterogeneous sources is a challenging issue to effectively exploit the numerous sources available on-line in global information systems. In this paper, we propose intelligent, tool-supported techniques to information extraction and integration from both structured and semistructured data sources. An object-oriented language, with an underlying Description Logics, called ODL I 3 , derived from the standard ODMG is introduced for information extraction. ODL I 3 descriptions of the source schemas are exploited first to set a shared vocabulary for the sources. Information integration is then performed in a semi-automatic way, by exploiting ODL I 3 descriptions of source schemas with a combination of Description Logics and clustering techniques and gives rise to a virtual integrated view of multiple sources. As the ultimate goal of providing an integrated view is querying the view, inde...

. Information sharing from multiple heterogeneous sources is a challenging issue which ranges from database to ontology areas. In this paper, we propose an intelligent approach to information integration which takes into account semantic conflicts and contradictions, caused by the lack of a common shared ontology. Our goal is to provide an integrated access to information sources, allowing a user to pose a single query and to receive a single unified answer. We propose a "semantic" approach to integration where the conceptual schema of each source is provided, adopting a common standard data model and language, and Description Logics plus clustering techniques are exploited. Description Logics is used to obtain a semi-automatic generation of a Common Thesaurus (to solve semantic heterogeneities and to derive a common ontology). Clustering techniques are used to build the global schema, i.e. the unified view of the data to be used for query processing. keywords: Intelligent Informat...

Developing intelligent tools for the integration of information extracted from multiple heterogeneous sources is a challenging issue to e ectively exploit the numerous sources available on-line in global information systems. In this paper, we propose intelligent, tool-supported techniques to information extraction and integration from both structured and semistructured data sources. An object-oriented language, with an underlying Description Logics, called ODLI3, derived from the standard ODMG is introduced for information extraction. ODLI3 descriptions of the source schemas are exploited rst to set a shared vocabulary for the sources. Information integration is then performed in a semi-automatic way, by exploiting ODLI3 descriptions of source schemas with a combination of Description Logics and clustering techniques and gives rise to a virtual integrated view of multiple sources. As the ultimate goal of providing an integrated view is querying the view, independently from the location/heterogeneity of the sources, a module for the reformulation of queries at the sources with semantic optimization capabilities is provided. Integration techniques described in the paper have been implemented in the MOMIS system, based on a conventional mediator architecture.