Tractable Reasoning and Conjunctive Query Answering for Defeasible DL-Lite under Rational Closure

2026-06-23

AI Summary

This work addresses the challenge of efficiently implementing defeasible reasoning based on rational closure and answering conjunctive queries in lightweight description logics, specifically DL-Lite and its core and Horn variants. To this end, the authors propose a plug-in architecture that seamlessly integrates non-monotonic reasoning on top of existing classical reasoners. This approach constitutes the first computationally efficient solution for rational closure reasoning in DL-Lite, achieving tractable instance checking and conjunctive query answering with only minimal additional overhead. By doing so, it substantially enhances the practical applicability of non-monotonic semantics in real-world knowledge representation systems.

Abstract

In Description Logics (DLs), reasoning under Rational Closure (RC) is a well-known and widely accepted non-monotonic formalism to handle defeasible knowledge. In this paper, we study the application of RC to the core and horn variants of the DL-Lite family of lightweight description logics. We analyze both entitlement (instance checking) and Conjunctive Query (CQ) answering under RC. Our main contribution is providing a plug-in architecture that builds upon existing standard classical reasoners, establishing that reasoning and CQ answering under RC for DL-Lite can be done efficiently with minimal computational overhead.

Problem

• Defeasible Reasoning
• DL-Lite
• Rational Closure
• Conjunctive Query Answering
• Non-monotonic Reasoning

Innovation

• Rational Closure
• DL-Lite
• Conjunctive Query Answering
• Non-monotonic Reasoning
• Plug-in Architecture