
318
Sadri
and
Kowalski
form — P(x! ..x
n
) for every n-ary predicate Ρ in the underlying language
which is not defined in the database (i.e., does not occur in the conclusion of a
deductive rule). In practice, for convenience, only the database is represented
explicitly and reasoning with its completion is implemented through the nega-
tion as finite failure rule (Clark [1978]).
Our method appeals to an alternative definition of constraint satisfaction.
According to this definition, a database D satisfies integrity constraints I if and
only if the completion of D is consistent with I. We call this the consistency
view of constraint satisfaction ...