Explanations for Negative Query Answers under Inconsistency-Tolerant Semantics

Explanations for Negative Query Answers under Inconsistency-Tolerant Semantics

Thomas Lukasiewicz, Enrico Malizia, Cristian Molinaro

Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence
Main Track. Pages 2705-2711. https://doi.org/10.24963/ijcai.2022/375

Inconsistency-tolerant semantics have been proposed to provide meaningful query answers even in the presence of inconsistent knowledge. Recently, explainability has also become a prominent problem in different areas of AI. While the complexity of inconsistency-tolerant semantics is rather well-understood, not much attention has been paid yet to the problem of explaining query answers when inconsistencies may exist. Recent work on existential rules in the inconsistent setting has focused only on understanding why a query is entailed. In this paper, we address another important problem, which is explaining why a query is not entailed under an inconsistency-tolerant semantics. In particular, we consider three popular semantics, namely, the ABox repair, the intersection of repairs, and the intersection of closed repairs. We provide a thorough complexity analysis for a wide range of existential rule languages and for several complexity measures.
Keywords:
Knowledge Representation and Reasoning: Computational Complexity of Reasoning