In this report we formalize a new method that checks Query
Containment for queries with negated IDB and EDB predicates as well as
equality, inequality and order comparisons. The generality of our
approach allows also our method to deal straightforwardly with query
containment under constraints. We prove soundness and completeness of
success and of failure of our method and we characterize the databases
where these properties hold.
Farre, C., Teniente, E., Urpi, T. "Formalization and correctness of the CQC method". 2002.