Imprecise Functional Dependencies

IntroductIon Functional dependencies represent a fundamental concept in the design of a database since they are capable of capturing some semantics of the data strongly connected with the occurrence of redundancy in a database. The development of applications working on fuzzy and multimedia databases has required the extension of the functional dependency notion to these new types of data. Unfortunately, the concept of imprecise functional dependence or fuzzy functional dependence (IFD, for short) has not had a cogent and largely accepted definition yet. In fact, in attempt to capture different aspects of this notion of many proposals of IFD definition exist in literature, all having semantics and objectives somewhat unclear, especially with respect to the on the definition of the concept of fuzzy functional dependency seems to be still in progress, as shown by the following question: " But the question remains: are these extended notions of functional dependency a natural generalization? " (Tyagi et al., 2005). The first problem that arises in the definition of a " well-defined " IFD is to avoid subjectivity. To this aim, in what follows, we report some pertinent dissertations from the literature. In particular, there is a conspicuous literature facing the problem of the definition of scientific concepts, and two behaviors are possible when the need for a new Imprecise Functional Dependencies definition arises. Firstly, according to the received view, the fact that scientists do not agree, shows that the definition has not been given yet up to now. In fact, for Carnap (1950), the procedure of explication is " the transformation of an inexact, prescientific concept, the explicandum, into a new exact concept, the explicatum. " (p. 3). Secondly, according to the analytic method view (Cellucci, 1998; Cellucci, 2000), a definition is always an ongoing process, as it is based on the formulation of a hypothesis. Within this philosophy, a definition of the concept of IFD has only to rely on the requirements of the specific problem that a person is facing. A better understanding of the concept of IFD is possible only by looking at the ongoing process of its definition, through a critical and unifying view. Therefore, the goal of this proposal is to present an overview of imprecise functional dependencies and to provide a critical discussion of the dependencies presented for fuzzy and multimedia data.