Towards fixed-parameter tractable algorithms for abstract argumentation

argumentation frameworks have received a lot of interest in recent years. Most computational problems in this area are intractable but several tradable fragments have been identified. In particular, Dunne showed that many problems can be solved in linear time for argumentation frameworks of bounded tree-width. However, these tractability results, which were obtained via Courcelle's Theorem, do not directly lead to efficient algorithms. The goal of this paper is to turn the theoretical tractability results into efficient algorithms and to explore the potential of directed notions of tree-width for defining larger tractable fragments. As a by-product, we will sharpen some known complexity results. (C) 2012 Elsevier B.V. All rights reserved.