SMODELS [Gelfond and Lifschitz, 1988]
DLV [Lifschitz and Woo, 1992]
Updates [Eiter et al., 2002]
U�Z(Π0, Π1) [Zhang, 2006]
Pairs of Updates [Guadarrama et al., 2005]
ODLP [Brewka et al., 2002, 2004]
AGM [Benferhat et al., 2004]