Matching dependencies (MDs) were introduced to specify the identification or
matching of certain attribute values in pairs of database tuples when some
similarity conditions are satisfied. Their enforcement can be seen as a natural
generalization of entity resolution. In what we call the "pure case" of MDs,
any value from the underlying data domain can be used for the value in common
that does the matching. We investigate the semantics and properties of data
cleaning through the enforcement of matching dependencies for the pure case. We
characterize the intended clean instances and also the "clean answers" to
queries as those that are invariant under the cleaning process. The complexity
of computing clean instances and clean answers to queries is investigated.
Tractable and intractable cases depending on the MDs and queries are
identified. Finally, we establish connections with database "repairs" under
integrity constraints.Comment: 13 pages, double column, 2 figure