Database Reference
In-Depth Information
Chapter VI
Fuzzy Aggregations and
Fuzzy Specializations in
Fuzzy EER Model
Jóse Galindo, Universidad de Málaga, Spain
Angélica Urrutia, Universidad Católica de Maule, Chile
Mario Piattini, Universidad de Castilla-La Mancha, Spain
ABSTRACT
Some approaches about fuzzy ER/EER model have been published recently. Few of these works
study how to relax constraints and other aspects expressed in the model. In this chapter our
aim is to relax some semantic aspects which have not been studied in previous works and to
extend the EER model with fuzzy capabilities. We use fuzzy quantifi ers and fuzzy degrees which
have been widely studied in the context of fuzzy sets and fuzzy query systems for databases.
We will also examine the representation of these new features in an EER model and their
practical repercussions. The studied extensions are: fuzzy aggregations and fuzzy aspects
on specializations, such as fuzzy degrees, fuzzy completeness constraint, fuzzy cardinality
constraint on overlapping specializations, fuzzy disjointed or overlapping constraints, fuzzy
attribute defi ned specializations, fuzzy constraints in union types or categories and fuzzy
constraints in shared subclasses (or intersection types). All these fuzzy extensions have a
new meaning and offer greater expressiveness in conceptual design.
INTRODUCTION
Conceptual modeling or design is a fundamental phase in the design of any database
(Elmasri & Navathe, 2000). In this phase of conceptual design the aim is to obtain the
so-called conceptual schema, which is a concise description of the data required by users,
including detailed description of the types of entities involved, the interrelationships existing
between them and also some important constraints in these relationships.
