We develop a model of abduction in abstract argumentation, where changes to an argumentation framework act as hypotheses to explain the support of an observation. We present dialogical proof theories for the main decision problems (i.e., finding hypothe- ses that explain skeptical credulous support) and we show that our model can be instantiated on the basis of abductive logic programs.
When several agents are engaged in an argumentation process, they are faced with the problem of deciding how to contribute to the current state of the debate in order to satisfy their own goal, ie. to make an argument under a given semantics accepted or not. In this paper, we study the minimal changes or target sets on the current state of the debate that are required to achieve such a goal, where changes are the addition and or deletion of attacks among arguments. We study some properties of these target sets, and propose a Maude specification of rewriting rules which allow to compute all the target sets for some types of goals.