Allowing Abstention

A semantics σ\sigma satisfies Allowing Abstention iff whenever an argument aa is in one extension E1∈σ(F)E_1 \in \sigma(F) and attacked by another E2∈σ(F)E_2 \in \sigma(F), there is an extension E3∈σ(F)E_3 \in \sigma(F) with a∉E3∪E3+a \notin E_3 \cup E_3^+.

Reference

Baroni, P., Caminada, M. & Giacomin, M. (2011). An Introduction to Argumentation Semantics. The Knowledge Engineering Review, 26(4), pp. 365–410.