On the entailment problem for DL-Lite${}_{core}$ ontologies and conjunctive queries with negation

Abstract

We show that the entailment problem, for a given entailment problem for DL-Lite${}_{core}$ ontology, and given conjunctive query with inequalities, is undecidable. We also show that this problem remains undecidable if conjunctive queries with safe negation are considered instead of conjunctive queries with inequalities.

Draft, no introduction and preliminaries; small fixes + better example