In the context of Dung's argumentation framework, we propose a general recursive schema for argumentation semantics, based on decomposition along the strongly connected components of the argumentation framework. We introduce the fundamental notion of SCC-recursiveness and show that all Dung's admissibility-based semantics are SCC-recursive, and therefore a special case of our schema. The space of SCC-recursive semantics provides a basis for the investigation of novel proposals: starting from the analysis of several examples where Dung's preferred semantics gives rise to counterintuitive results, we introduce four novel SCC-recursive semantics, able to overcome the limitations of preferred semantics, while differing in other respects. Among them, the CF2 semantics, which more radically departs from the traditional notion of admissibility, turns out to be the most satisfactory in all cases and, in particular, is able to correctly deal with the thorny problem of self-defeating arguments.
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