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A first approach to the multipurpose relational database server.

Ignacio J. Blanco, Carmen Martínez-Cruz, José María Serrano, M. Amparo Vila (2005)

Mathware and Soft Computing

In this paper, an architecture and an implementation of a multipurpose relational database server are proposed. This architecture enables classical queries to be executed, deductions to be made, and data mining operations to be performed on fuzzy or classical data. The proposal of this integration is to combine several ways of querying different types of data. In order to achieve this, a combination of existing meta-knowledge bases and new data catalog elements is presented. We also introduce a...

A generalisation of entity and referential integrity in relational databases

Mark Levene, George Loizou (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Entity and referential integrity are the most fundamental constraints that any relational database should satisfy. We re-examine these fundamental constraints in the context of incomplete relations, which may have null values of the types “value exists but is unknown” and “value does not exist”. We argue that in practice the restrictions that these constraints impose on the occurrences of null values in relations are too strict. We justify a generalisation of the said constraints wherein we use...

A Generalisation of Entity and Referential Integrity in Relational Databases

Mark Levene, George Loizou (2010)

RAIRO - Theoretical Informatics and Applications

Entity and referential integrity are the most fundamental constraints that any relational database should satisfy. We re-examine these fundamental constraints in the context of incomplete relations, which may have null values of the types "value exists but is unknown" and "value does not exist" . We argue that in practice the restrictions that these constraints impose on the occurrences of null values in relations are too strict. We justify a generalisation of the said constraints wherein we use...

A rough set-based knowledge discovery process

Ning Zhong, Andrzej Skowron (2001)

International Journal of Applied Mathematics and Computer Science

The knowledge discovery from real-life databases is a multi-phase process consisting of numerous steps, including attribute selection, discretization of real-valued attributes, and rule induction. In the paper, we discuss a rule discovery process that is based on rough set theory. The core of the process is a soft hybrid induction system called the Generalized Distribution Table and Rough Set System (GDT-RS) for discovering classification rules from databases with uncertain and incomplete data....

Codes that attain minimum distance in every possible direction

Gyula Katona, Attila Sali, Klaus-Dieter Schewe (2008)

Open Mathematics

The following problem motivated by investigation of databases is studied. Let 𝒞 be a q-ary code of length n with the properties that 𝒞 has minimum distance at least n − k + 1, and for any set of k − 1 coordinates there exist two codewords that agree exactly there. Let f(q, k)be the maximum n for which such a code exists. f(q, k)is bounded by linear functions of k and q, and the exact values for special k and qare determined.

Comparing the succinctness of monadic query languages over finite trees

Martin Grohe, Nicole Schweikardt (2004)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We study the succinctness of monadic second-order logic and a variety of monadic fixed point logics on trees. All these languages are known to have the same expressive power on trees, but some can express the same queries much more succinctly than others. For example, we show that, under some complexity theoretic assumption, monadic second-order logic is non-elementarily more succinct than monadic least fixed point logic, which in turn is non-elementarily more succinct than monadic datalog. Succinctness...

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