On the operations over relations in the relational model data with two types of null values.
Pavlović, Gordana M. (1983)
Publications de l'Institut Mathématique. Nouvelle Série
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Displaying similar documents to “Relational specifications”
On the operations over relations in the relational model data with two types of null values.
Towards specifying with inclusions.
Jaume Agustí, Jordi Puigsegur, W. Marco Schorlemmer (1997)
Mathware and Soft Computing
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In this article we present a functional specification language based on inclusions between set expressions. Instead of computing with data individuals we deal with their classification into sets. The specification of functions and relations by means of inclusions can be considered as a generalization of the conventional algebraic specification by means of equations. The main aim of this generalization is to facilitate the incremental refinement of specifications. Furthermore, inclusional...
On ω-models which are not β-models
Andrzej Mostowski, Y. Suzuki (1969)
Fundamenta Mathematicae
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Attributes, sets, partial sets and identity
P. C. Gilmore (1968)
Compositio Mathematica
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An algebraic characterization of quantifiers
Leon Henkin (1950)
Fundamenta Mathematicae
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States of affairs as values for formulas
Miroslav Mleziva (1975)
Kybernetika
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Mental models, model-theoretic semantics, and the psychosemantic conception of truth
Shira Elqayam (2005)
Philosophia Scientiae
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Repetitions and permutations of columns in the semijoin algebra
Dirk Leinders, Jan Van Den Bussche (2009)
RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications
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Codd defined the relational algebra [E.F. Codd, Communications of the ACM 13 (1970) 377–387; E.F. Codd, Relational completeness of data base sublanguages, in Data Base Systems, R. Rustin, Ed., Prentice-Hall (1972) 65–98] as the algebra with operations projection, join, restriction, union and difference. His projection operator can drop, permute and repeat columns of a relation. This permuting and repeating of columns does not really add expressive power to the relational algebra. Indeed,...
A logic-based environment for developing natural language processing applications
Gérard Milhaud, Élisabeth Godbert (1998)
Mathématiques et Sciences Humaines
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We present a system providing a set of tools for developing natural language processing (NLP) applications such as natural language interfaces, communication aid systems, etc. This system is based on two principles: modularity of knowledge representation to ensure the portability of the system, and guided sentence composition to ensure transparency, i.e. to ensure that the produced sentences are well-formed at the lexical, syntactic, semantic and conceptual levels. We first describe...