It is a well-known fact that stable semantics might not provide any extensions for some given abstract argumentation framework. Arguably such frameworks might be considered futile, at least with respect to stable semantics. We propagate σ -perfection stating that for a given argumentation graph all induced subgraphs provide σ -extensions. We discuss perfection and conditions for popular abstrac...

3 From the Editors trail documenting what the system is supposed to do (and not supposed to do), why the design should work, and what assumptions are being made. So, to hold software producers accountable, we need a mature discipline of forensics for computing systems and components. But getting there will require some radical changes in software development practices, since in addition to deli...

Two non-adjacent vertices x and y in a graph G form an even pair if every induced path between them has an even number of edges. For a given pair fx; yg in a graph G, we denote by G xy the graph obtained from G by contracting x and y. In 1982, Fonlupt and Uhry proved that if G is perfect then so is G xy. In 1987, Meyniel used this fact to prove that no minimal imperfect graph contains an even p...

A holographic description of chiral symmetry breaking in the pattern of QCD is reviewed. D7 brane probes are used to include quark fields in a simple non-supersymmetric deformation of the AdS/CFT Correspondence. The axial symmetry breaking is realized geometrically and the quark condensate and meson masses are computable. Surprisingly, treating the model as a description of QCD works quantitati...

A strategy activated in one task may be transferred to subsequent tasks and prevent activation of other strategies that would otherwise come to mind, a mechanism referred to as procedural priming. In a novel application of procedural priming we show that it can make or break cognitive illusions. Our test case is the 1/k illusion, which is based on the same unwarranted mathematical shortcut as t...

Computing the chromatic number and finding an optimal coloring of a perfect graph can be done efficiently, whereas it is an NP-hard problem in general. Furthermore, testing perfection can be carriedout in polynomial-time. Perfect graphs are characterized by a minimal structure of their stable set polytope: the non-trivial facets are defined by clique inequalities only. Conversely, does a simila...