Topological relations have played important roles in spatial query, analysis and reasoning in Geographic Information Systems (GIS) and spatial databases. The topological relations between crisp and fuzzy spatial objects based upon the 9intersections topological model have been identified. However the formalization of the topological relations between fuzzy regions needs more investigation. The ...

FLOPER is the “Fuzzy LOgic Programming Environment for Research” designed in our research group for assisting the development of real-world applications where fuzzy logic might play an important role. This is the case of our recently proposed extension for the popular XPath query language in order to handle flexible queries which provide ranked answers, fuzzy variants of operators and, or and a...

This paper shows how a Fuzzy Ontology based approach can improve semantic documents retrieval. After formally defining a Fuzzy Knowledge Base, it is discussed a special type of new non-taxonomic fuzzy relationships, called (semantic) correlations. These correlations, first assigned by experts, are updated after querying, or when a document has been inserted into a database. It is then introduce...

Fuzzy sets and rough sets address two important, and mutually orthogonal, characteristics of imperfect data and knowledge: while the former allow that objects belong to a set or relation to a given degree, the latter provide approximations of concepts in the presence of incomplete information. In this chapter, we demonstrate how these notions can be combined into a hybrid theory that is able to...

Information Systems, and in particular Current Research Information Systems (CRISs), are usually quite difficult to query when looking for specific information, due to the huge amounts of data they contain. To solve this problem, we propose to use a personal search agent that uses fuzzy and rough sets to inform the user about newly available information. Additionally, in order to automate the o...

The paper proposes an indexing technique for fuzzy numerical data which increases the performance of query processing when the query involves an atomic necessity measured flexible condition. The proposal is based on a classical indexing technique for numerical crisp data, B+tree. Its efficiency is contrasted with another indexing method for similar data and queries. Results show that the propos...

Structured Query Language (SQL) is used to obtain data from relational databases. Fuzzy improvement of SQL queries has advantages in cases when the user cannot unambiguously define selection criteria or when the user wants to examine data that almost meet the given criteria. In this paper we examine a realisation of the fuzzy querying concept. For this purposes the fuzzy generalized logical con...

In order to make more flexible database access the query language SQLf has been previously proposed. One of the SQLf features is the use of Fuzzy Quantifiers in Having Clause. For this kind of query, three evaluation mechanisms have been proposed: the Naïve, the Sugeno Integral Heuristics based and the Alfa-cut Derivation based. We present in this paper a formal performance study of these three...

Providing efficient query processing in database systems is one step in gaining acceptance of such systems by end users. We propose several techniques for indexing fuzzy sets in databases to improve the query evaluation performance. Three of the presented access methods are based on superimposed coding, while the fourth relies on inverted files. The efficiency of these techniques was evaluated ...

In this study, a multimedia database system which includes a semantic content extractor, a high-dimensional index structure and an intelligent fuzzy object-oriented database component is proposed. The proposed system is realized by following a component-oriented approach. It supports different flexible query capabilities for the requirements of video users, which is the main focus of this paper...