Labelling

A labelling is a total function $L \colon A \to \{\mathsf{in}, \mathsf{out}, \mathsf{undec}\}$; an argument $a$ is accepted, rejected, or undecided in $L$ if $L(a)$ is $\mathsf{in}$, $\mathsf{out}$, or $\mathsf{undec}$, respectively.