Three-Valued Model (ADF)

A three-valued interpretation $v$ of an ADF is a three-valued model iff $v(a) \neq \mathsf{u}$ implies $v(a) = v(C_a)$ for all $a \in A$, where $v(C_a)$ is evaluated in Kleene's strong three-valued logic: negation switches $\mathsf{t}$ and $\mathsf{f}$ and leaves $\mathsf{u}$ unchanged, a conjunction is $\mathsf{t}$ if both conjuncts are $\mathsf{t}$, $\mathsf{f}$ if some conjunct is $\mathsf{f}$, and $\mathsf{u}$ otherwise; disjunction is dual.