After the submission of the camera ready paper, the following two references have come to our attention:

These papers propose an alternative solution to that proposed in:

While our paper contains no technical errors or mistakes, it should be noted that the approach proposed in Section 3.1 is designed only for syntactically restricted programs. For a more general solution to the general problem of providing a declarative semantics to Datalog programs when aggregates are used in the recursive definition of predicates we refer the reader to the references above.