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

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.