Someone slept in my bed! On the entailment problem for conjunctive queries with safe negation over DL-Lite$_{core}$ knowledge bases

The authors address a long-standing question in computer science related to answering specific types of database questions, called conjunctive queries with safe negation, when using DL-Lite_core, a lightweight logic for representing knowledge bases. They prove that checking if these queries can be answered or not is undecidable, meaning there is no general algorithm that can solve the problem for all cases. This result shows inherent limits on the capabilities of automated reasoning within this framework.