Verifiability of Argumentation Semantics
  Dung's abstract argumentation theory is a widely used formalism to model
conflicting information and to draw conclusions in such situations. Hereby, the
knowledge is represented by so-called argumentation frameworks (AFs) and the
reasoning is done via semantics extracting acceptable sets. All reasonable
semantics are based on the notion of conflict-freeness which means that
arguments are only jointly acceptable when they are not linked within the AF.
In this paper, we study the question which information on top of conflict-free
sets is needed to compute extensions of a semantics at hand. We introduce a
hierarchy of so-called verification classes specifying the required amount of
information. We show that well-known standard semantics are exactly verifiable
through a certain such class. Our framework also gives a means to study
semantics lying inbetween known semantics, thus contributing to a more abstract
understanding of the different features argumentation semantics offer.
