 Circumscription is a special case of a wider class of defeasible logics, the preferential logics (Shoham 1987). In preferential logics, \(\Gamma \dproves p\) iff \(p\) is true in all of the most preferred models of \(\Gamma\). In the case of circumscription, the most preferred models are those that minimize the extension of certain predicates, but many other kinds of preference relations can be used instead, so long as the preference relations are transitive and irreflexive (a strict partial order). A structure consisting of a set of models of a propositional or first-order language, together with a preference order on those models, is called a preferential structure. The symbol \(\prec\) shall represent the preference relation. \(M \prec M'\) means that \(M\) is strictly preferred to \(M'\). A most preferred model is one that is minimal in the ordering.