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Representative instances and γ-acyclic relational schemes | IEEE Journals & Magazine | IEEE Xplore

Representative instances and γ-acyclic relational schemes


Abstract:

In this paper, we study under what conditions will a pairwise inconsistent relational database ≪R,r≫ have a universal/representative instance L. If R is γ-acyclic and r s...Show More

Abstract:

In this paper, we study under what conditions will a pairwise inconsistent relational database ≪R,r≫ have a universal/representative instance L. If R is γ-acyclic and r satisfies all existence constraints, then it is possible to construct a universal instance L, using unmarked nulls, whose total projections onto R yield exactly the relations in r. We show that L would actually be a representative instance under a set of functional dependencies if R satisfies the additional mild condition: for any functional dependency X → A where A is a single attribute, whenever XA is contained in two relation schemes R and R' of R, it follows that R ∩R' is a relation scheme of R, having X as one of its keys.
Published in: IEEE Transactions on Software Engineering ( Volume: SE-10, Issue: 6, November 1984)
Page(s): 614 - 618
Date of Publication: 29 May 2009

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