Aykut Firat

Fuzzy objects for geographical information systems

Abstract Modeling, storing and retrieving geographical information has become an important part of our information society. Geographical information is typically specified in terms of collections of entities and phenomena that are structured aggregations of spatial entities. GIS features tend to form natural class hierarchies. Another characteristic of geographical information is that often it may be inexact or vague. With respect to these characteristics, the confluence of the two technologies fuzzy set theory and object-oriented databases could provide a powerful tool for knowledge representation underlying geographical information systems. The fuzzy object data model is currently being developed and prototype implementations have been undertaken using an integrative approach with existing software including an expert system shell and a commercial object-oriented database system. In this paper, the benefits of a fuzzy object data model for geographical information systems are examined, an overview of the model is presented, and the current prototype implementations are described.

Contextual alignment of ontologies in the eCOIN semantic interoperability framework

The prospect of combining information from diverse sources for superior decision making is plagued by the challenge of semantic heterogeneity, as data sources often adopt different conventions and interpretations when there is no coordination. An emerging solution in information integration is to develop an ontology as a standard data model for a domain of interest, and then to define the correspondences between the data sources and this common model to eliminate their semantic heterogeneity and produce a single integrated view of the data sources. We first claim that this single integrated view approach is unnecessarily restrictive, and instead offer the view that ontologies can simultaneously accommodate multiple integrated views provided the accompaniment of contexts, a set of axioms on the interpretation of data allowing local variations in representation and nuances in meaning, and a conversion function network between contexts to reconcile contextual differences. Then, we illustrate how to achieve semantic interoperability between multiple ontology-based applications. During this process, application ontologies are aligned through the reconciliation of their context models, and a new application with a virtual merged ontology is created. We illustrate this alternative approach with the alignment of air travel and car rental domains, an actual example from our prototype implementation.

Information aggregation using the caméléon# web wrapper

Cameleon# is a web data extraction and management tool that provides information aggregation with advanced capabilities that are useful for developing value-added applications and services for electronic business and electronic commerce. To illustrate its features, we use an airfare aggregation example that collects data from eight online sites, including Travelocity, Orbitz, and Expedia. This paper covers the integration of Cameleon# with commercial database management systems, such as MS SQL Server, and XML query languages, such as XQuery.

General Strategy for Querying Web Sources in a Data Federation Environment

Modern database management systems are supporting the inclusion and querying of non-relational sources within a data federation environment via wrappers. Wrapper development for Web sources, however, is a convolution of code with extraction and query planning knowledge and becomes a daunting task. We use IBM DB2 federation engine to demonstrate the challenges of incorporating Web sources into a data federation. We, then, present a practical and general strategy for the inclusion and querying of Web sources without requiring any changes in the underlying data federation technology. This strategy separates the code and knowledge in wrapper development by introducing a general-purpose capabilities-aware mini query-planner and a data extraction engine. As a result, Web sources can be included in a data federation system faster, and maintained easier.