Admissibility

A set $E \subseteq A$ is admissible iff $E$ is conflict-free and defends every $a \in E$.

Signature

A set $\mathbb{S}$ of sets of arguments is in $\mathsf{sig}(\mathsf{ad})$ iff $\emptyset \in \mathbb{S}$ and $\mathbb{S}$ is conflict-sensitive (Dunne et al., 2015).