17,992 research outputs found
Implementing imperfect information in fuzzy databases
Information in real-world applications is often
vague, imprecise and uncertain. Ignoring the inherent imperfect
nature of real-world will undoubtedly introduce some deformation of human perception of real-world and may eliminate several
substantial information, which may be very useful in several
data-intensive applications. In database context, several fuzzy
database models have been proposed. In these works, fuzziness
is introduced at different levels. Common to all these proposals is
the support of fuzziness at the attribute level. This paper proposes
ïŹrst a rich set of data types devoted to model the different kinds
of imperfect information. The paper then proposes a formal
approach to implement these data types. The proposed approach
was implemented within a relational object database model but it
is generic enough to be incorporated into other database models.ou
Conceptual design and implementation of the fuzzy semantic model
FSM is one of few database models that support
fuzziness, uncertainty and impreciseness of real-world at the class
deïŹnition level. FSM authorizes an entity to be partially member
of its class according to a given degree of membership that reïŹects
the level to which the entity veriïŹes the extent properties of this
class. This paper deals with the conceptual design of FSM and
adresses some implementation issues.ou
Some notes on an extended query language for FSM
FSM is a database model that has been recently proposed by the authors. FSM uses basic concepts of
classification, generalization, aggregation and association that are commonly used in semantic modelling and
supports the fuzziness of real-world at attribute, entity, class and relations intra and inter-classes levels. Hence, it
provides tools to formalize and conceptualize real-world within a manner adapted to human perception of and
reasoning about this real-word. In this paper we briefly review basic concepts of FSM and provide some notes on an
extended query language adapted to it.ou
Using Fuzzy Linguistic Representations to Provide Explanatory Semantics for Data Warehouses
A data warehouse integrates large amounts of extracted and summarized data from multiple sources for direct querying and analysis. While it provides decision makers with easy access to such historical and aggregate data, the real meaning of the data has been ignored. For example, "whether a total sales amount 1,000 items indicates a good or bad sales performance" is still unclear. From the decision makers' point of view, the semantics rather than raw numbers which convey the meaning of the data is very important. In this paper, we explore the use of fuzzy technology to provide this semantics for the summarizations and aggregates developed in data warehousing systems. A three layered data warehouse semantic model, consisting of quantitative (numerical) summarization, qualitative (categorical) summarization, and quantifier summarization, is proposed for capturing and explicating the semantics of warehoused data. Based on the model, several algebraic operators are defined. We also extend the SQL language to allow for flexible queries against such enhanced data warehouses
- âŠ