 We say that \(w\) is an \(\alpha\)-minimal world iff \(w\in V(\alpha)\) and there is no \(v\in V(\alpha)\) such that \(v\prec w\). Every preferential model gives rise to a consequence relation by setting \(\alpha \dproves \beta\) whenever \(\beta\) is true in all the \(\alpha\)-minimal worlds. Kraus et al. (1990) prove the following: