“…For instance, adding arc(X, Y ) to the body establishes this condition for rule (4).) Unlike that, the DLV grounder (Leone, Pfeifer, Faber, Eiter, Gottlob, Perri, & Scarcello, 2006;Faber et al, 2012) and recent versions of GRINGO (Gebser, Kaminski, König, & Schaub, 2011a; are based on semi-naive bottom-up evaluation (cf. Abiteboul, Hull, & Vianu, 1995), only requiring safety, i.e., some occurrence in a positive precondition for each variable, to iteratively generate ground instances of recursive rules until no new head atoms are produced anymore.…”