Title :
Representative instances and γ-acyclic relational schemes
Author :
Jajodia, Sushil ; Ng, Peter A.
Author_Institution :
Department of Computer Science, University of Missouri, Columbia., MO 65211.
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.
Keywords :
Database systems; Fault detection; Relational databases; γ-acyclic relational scheme; representative instance; universal instance; universal instance assumption;
Journal_Title :
Software Engineering, IEEE Transactions on
DOI :
10.1109/TSE.1984.5010290