Justifications and Blocking Sets in a Rule-Based Answer Set Computation
Christopher Béatrix, Claire Lefèvre, Laurent Garcia, Igor Stéphan · DROPS (Schloss Dagstuhl – Leibniz Center for Informatics) · 2016
Notions of justifications for logic programs under answer set semantics have been recently studied for atom-based approaches or argumentation approaches. The paper addresses the question in a rule-based answer set computation: the search algorithm does not guess on the truth or falsity of an atom but on the application or non application of a non monotonic rule. In this view, justifications are sets of ground rules with particular properties. Properties of these justifications are established; in particular the notion of blocking set (a reason incompatible with an answer set) is defined, that permits to explain computation failures. Backjumping, learning, debugging and explanations are possible applications.