Expanding queries to incomplete databases by interpolating
general logic programs
Chitta Baral, Michael Gelfond and Olga Kosheleva
Abstract
In databases, queries are usually defined on complete databases.
In this paper we introduce and motivate the notion of extended
queries that are defined on incomplete databases.
We argue that the language of extended logic program
is appropriate for representing extended queries.
We show through examples that given a query,
a particular extension of it has important characteristics
which corresponds to removal of the CWA from the
original specification of the query.
We refer to this particular extension as the {\em expansion}
of the original query.
Normally queries are expressed as general logic programs.
We develop an algorithm that given a general logic program
(satisfying certain syntactic properties)
expressing a query constructs an extended logic program
that expresses the expanded query. The extended logic program is
referred to as the {\em interpolation} of the given
general logic program.