  This paper present several refinements of the Datalog +/- framework based on
resolution and Datalog-rewriting. We first present a resolution algorithm which
is complete for arbitrary sets of tgds and egds. We then show that a technique
of saturation can be used to achieve completeness with respect to First-Order
(FO) query rewriting. We then investigate the class of guarded tgds (with a
loose definition of guardedness), and show that every set of tgds in this class
can be rewritten into an equivalent set of standard Datalog rules. On the
negative side, this implies that Datalog +/- has (only) the same expressive
power as standard Datalog in terms of query answering. On the positive side
however, this mean that known results and existing optimization techniques
(such as Magic-Set) may be applied in the context of Datalog +/- despite its
richer syntax.
