 This problem has been tackled in  Lehmann (1995)  with the formalism Lexicographic Closure. Rougly the idea is to compare models by measuring the severity of violations of assertions in the given conditional knowledge base to which they give rise. \(\phi \nc \psi\) is entailed by \(\mathbf{K}\) if the best models of \(\phi \wedge \psi\) are better than the best models of \(\phi \wedge \neg \psi\). A model \(M\) violates a conditional assertion \(\phi \nc \psi\) if it validates \(\phi\) but not \(\psi\). The violation is the more severe the higher the rank of \(\phi\). For instance, in our example we have the following models of \(l \wedge f\) resp. of \(l \wedge \neg f\): 