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|Title: ||FUNCTIONAL DEPENDENCIES AND INCOMPLETE INFORMATION|
|Authors: ||Vassiliou, Yannis|
|Issue Date: ||Oct-1980|
|Publisher: ||Stern School of Business, New York University|
|Series/Report no.: ||IS-81-08|
|Abstract: ||Functional dependencies play an important role in
relational database design. They are defined in the context
of a single relation which at all times must contain
tuples with non-null entries. In this paper we examine
an extension of the functional dependency interpretation
to handle null values, that is, entries in tuples that
represent incomplete information in a relational database.
A complete axiomatization of inference rules for
extended functional dependencies is also presented.
Only after having such results is it possible to talk about
decompositions and normalization theory in a context of
incomplete information. Finally, we show that there are
several practical advantages in using nulls and a weaker
notion of constraint satisfiability.|
|Appears in Collections:||IOMS: Information Systems Working Papers|
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