Fuzzy information systems

The authors discuss the issue of uncertainty management in conceptual, logical, and navigational data models. Two different approaches to conceptual modeling are examined, the extended IFO model and the extended entity relationship model. These models can represent complex objects with uncertainty in the attribute values chiefly with their powerful abstraction mechanisms. The logical models, specifically the first normal form (1NF) model and the non-1NF data model, are also discussed in detail. The question of representing and manipulating impression in navigational models, i.e. network and object-oriented data models, is considered