What makes propositional abduction tractable

Abduction is a fundamental form of nonmonotonic reasoning that aims at finding explanations for observed manifestations. This process underlies many applications, from car configuration to medical diagnosis. We study here the computational complexity of deciding whether an explanation exists in the case when the application domain is described by a propositional knowledge base. Building on previous results, we classify the complexity for local restrictions on the knowledge base and under various restrictions on hypotheses and manifestations. In comparison to the many previous studies on the complexity of abduction we are able to give a much more detailed picture for the complexity of the basic problem of deciding the existence of an explanation. It turns out that depending on the restrictions, the problem in this framework is always polynomial-time solvable, NP-complete, coNP-complete, or P 2 -complete. Based on these results, we give an a posteriori justification of what makes propos...

• Type: Journal
• Year: 2008
• Where: AI
• Authors: Gustav Nordh, Bruno Zanuttini
• Keywords: AI 2008, Artificial Intelligence, Computational Complexity, Knowledge Bases, Propositional Knowledge Base