$m$ is a *typical model* of $S$. $\Box$

A system $S$ may have no most typical model, but every $S$ has a typical one. Indeed, every typical atom $\hat{a}$ is consistent with $S$, so there is a model $m$ containing $\hat{a}$. Either $m$ is a typical model of $S$ or there is a typical model $\mu$ such that $T(m) \subset
T(\mu)$.

Suppose, a reasoner $R$ prefers a model $m$ assuming that it describes most trustfully the present possible world $w$. Then $m$ represents the set of $R$’s beliefs, but because of incompleteness of $S$ some of the beliefs may be false in $w$.

A formula $F$ is false in a possible world $w$ with probability $1 - p(F)$ (expression (1)). Let the *erratum* $ER(A)$ of a set of literals $A$ be the expected proportion of its literals that are false in a randomly chosen possible world $w$. Then taking $E(S, l)$ as an approximation of $p(l)$ we get $$ER(A) = 1 - \frac{1}{|A|} \sum_{l \in A} E(S, l).$$

\[th-typmod\] (i) For all $m \in MOD(S)$ there is a typical model $\mu$ of $S$ such that $ER(\mu) \le ER(m)$.

\(ii) If $\mu$ is the most typical model of $S$ then for 