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117
S.: Object normal forms and dependency constraints for objectoriented schemata
 ACM Trans. Database Syst
, 1997
"... We address the development of a normalization theory for objectoriented data models that have common features to support object identity and complex objects. We first provide an extension of functional dependencies to cope with the richer semantics of relationships between objects, called path depe ..."
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Cited by 32 (1 self)
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We address the development of a normalization theory for objectoriented data models that have common features to support object identity and complex objects. We first provide an extension of functional dependencies to cope with the richer semantics of relationships between objects, called path dependency, local dependency, and global dependency constraints. Using these dependency constraints, we provide normal forms for objectoriented data models based on the notions of user interpretation (userspecified dependency constraints) and object model. In contrast to conventional data models in which a normalized object has a unique interpretation, in objectoriented data models, an object may have many multiple interpretations that form the model for that object. An object will then be in a normal form if and only if the user’s interpretation is derivable from the model of the object. Our normalization process is by nature iterative, in which objects are restructured until their models reflect the user’s interpretation.
Inclusion and exclusion dependencies in team semantics: On some logics of imperfect information
 Annals of Pure and Applied Logic, 163(1):68
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Extending Existing Dependency Theory to Temporal Databases
 IEEE Trans. on Knowledge and Data Engineering
, 1994
"... Normal forms play a central role in the design of relational databases. Several normal forms for temporal relational databases have been proposed. These definitions are particular to specific temporal data models, which are numerous and incompatible. ..."
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Cited by 23 (8 self)
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Normal forms play a central role in the design of relational databases. Several normal forms for temporal relational databases have been proposed. These definitions are particular to specific temporal data models, which are numerous and incompatible.
Normal Forms for Defeasible Logic
 In Proc. Joint International Conference and Symposium on Logic Programming
, 1998
"... Defeasible logic is an important logicprogramming based nonmonotonic reasoning formalism which has an efficient implementation. It makes use of facts, strict rules, defeasible rules, defeaters, and a superiority relation. Representation results are important because they can help the assimilation o ..."
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Cited by 21 (13 self)
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Defeasible logic is an important logicprogramming based nonmonotonic reasoning formalism which has an efficient implementation. It makes use of facts, strict rules, defeasible rules, defeaters, and a superiority relation. Representation results are important because they can help the assimilation of a concept by confining attention to its critical aspects. In this paper we derive some representation results for defeasible logic. In particular we show that the superiority relation does not add to the expressive power of the logic, and can be simulated by other ingredients in a modular way. Also, facts can be simulated by strict rules. Finally we show that we cannot simplify the logic any further in a modular way: Strict rules, defeasible rules, and defeaters form a minimal set of independent ingredients in the logic. 1 Introduction Normal forms play an important role in computer science. Examples of areas where normal forms have proved fruitful include logic [10], where normal forms o...
Functional Dependencies in a Relational Database and Propositional Logic
 IBM Journal of Research and Development
, 1977
"... Abstract: An equivalence is shown between functional dependency statements of a relational database, where “+ ” has the meaning of “determines, ” and implicational statements of propositional logic, where “.$ ” has the meaning of “implies. ” Specifically, it is shown that a dependency statement is a ..."
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Cited by 21 (1 self)
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Abstract: An equivalence is shown between functional dependency statements of a relational database, where “+ ” has the meaning of “determines, ” and implicational statements of propositional logic, where “.$ ” has the meaning of “implies. ” Specifically, it is shown that a dependency statement is a consequence of a set of dependency statements iff the corresponding implicational statement is a consequence of the corresponding set of implicational statements. The database designer can take advantage of this equivalence to reduce problems of interest to him to simpler problems in propositional logic. A detailed algorithm is presented for such an application. Two proofs of the equivalence are presented: a “syntactic ” proof and a “semantic ” proof. The syntactic proof proceeds in several steps. It is shown that I) Armstrong’s Dependency Axioms are complete for dependency statements in the usual logical sense that they are strong enough to prove every consequence, and that 2) Armstrong’s Axioms are also complete for implicational statements in propositional logic. The equivalence then follows from 1) and 2). The other proof proceeds by considering appropriate semantic interpretations for the propositional variables. The DelobelCasey Relational Database Decomposition Theorems, which heretofore have seemed somewhat fortuitous, are immediate and natural corollaries of the equivalence. Furthermore, a counterexample is demonstrated, which shows that what seems to be a mild extension of the equivalence fails.
Unique complements and decompositions of database schemata
 Journal of Computer and System Sciences
, 1994
"... In earlier work, Bancilhon and Spyratos introduced the concept of a complement to a database schema, and showed how this notion could be used in theories of decomposition and update semantics. However, they also showed that, except in trivial cases, even minimal complements are never unique, so that ..."
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In earlier work, Bancilhon and Spyratos introduced the concept of a complement to a database schema, and showed how this notion could be used in theories of decomposition and update semantics. However, they also showed that, except in trivial cases, even minimal complements are never unique, so that many desirable results, such as canonical decompositions, cannot be realized. Their work dealt with database schemata which are sets and database mappings which are functions, without further structure. In this work, we show that by adding a modest amount of additional structure, many important uniqueness results may be obtained. Specifically, we work with database schemata whose legal states form partially ordered sets (posets) with least elements, and with database mappings which are isotonic and which preserve this least element. This is a natural algebraic structure which is inherent in many important examples, including relational schemata constrained by data dependencies, with views constructed by composition of projection, restriction, and selection. Other examples include deductive database schemata in which views are defined by rules, and general firstorder logic databases.
Decomposition of a Data Base and the Theory of Boolean Switching Functions
 IBM Journal of Research and Development
, 1973
"... Abstract: The notion of a functional relation among the attributes of a data set can be fruitfully applied in the structuring of an information system. These relations are meaningful both to the user of the system in his semantic understanding of the data, and to the designer in implementing the sys ..."
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Cited by 16 (0 self)
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Abstract: The notion of a functional relation among the attributes of a data set can be fruitfully applied in the structuring of an information system. These relations are meaningful both to the user of the system in his semantic understanding of the data, and to the designer in implementing the system. An important equivalence between operations with functional relations and operations with analogous Boolean functions is demonstrated in this paper. The equivalence is computationally helpful in exploring the properties of a given set of functional relations, as well as in the task of partitioning a data set into subfiles for efficient implementation. 1.
Linearly Bounded Reformulations of Conjunctive Databases (Extended Abstract)
 In Proc. of DOOD
, 2000
"... Database reformulation is the process of rewriting the data and rules of a deductive database in a functionally equivalent manner. ..."
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Cited by 15 (6 self)
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Database reformulation is the process of rewriting the data and rules of a deductive database in a functionally equivalent manner.
A New Normal Form for the Design of Relational Database Schemata
 ACM TODS
, 1982
"... This paper addresses the problem of database schema design in the framework of the relational data model and functional dependencies. It suggests that both Third Normal Form (3NF) and BoyceCodd Normal Form (BCNF) supply an inadequate basis for relational schema design. The main problem with 3NF is t ..."
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This paper addresses the problem of database schema design in the framework of the relational data model and functional dependencies. It suggests that both Third Normal Form (3NF) and BoyceCodd Normal Form (BCNF) supply an inadequate basis for relational schema design. The main problem with 3NF is that it is too forgiving and does not enforce the separation principle as strictly as it should. On the other hand, BCNF is incompatible with the principle of representation and prone to computational complexity. Thus a new normal form, which lies between these two and captures the salient qualities of both is proposed. The new normal form is stricter than 3NF, but it is still compatible with the representation principle. First a simpler definition of 3NF is derived, and the analogy of this new definition to the definition of BCNF is noted. This analogy is used to derive the new normal form. Finally, it is proved that Bernstein's algorithm for schema design synthesizes schemata that are already in the new normal form