From Classical to Consistent Query Answering under Existential Rules

Answering conjunctive queries (CQs) over knowledge bases (KBs) containing dis- junctive existential rules is a relevant reasoning task which can be addressed using the disjunctive

Bienvenu, M., Rosati, R.: Tractable approximations of consistent query answering for robust ontology-based data access. In: Proceedings of the 23rd International Joint Conference

Since such atoms are not given as input, we address the problem of (e ffi ciently) computing such restricting atoms within an approximate query answering algorithm after showing

The best existing lower bounds for our problem are the following: (i) 2E XP T IME in combined complexity, and also E XP T IME in case of bounded arity, for guarded DTGDs [9], (ii) 2E

An important tool we use for analyzing the complexity of query answering is the notion of materializability of a TBox T , which means that computing the certain answers to any query

An important result of these works is that the main variants of DL-Lite are not only decidable, but that answering (unions of) conjunctive queries for these logics is in LOGSPACE ,

It is worth noticing that the data complexity of cautious query evaluation from disjunctive logic programs with stratified negation is the same as for disjunctive logic programs

Conjunctive query answering (CQA) is the task of finding all answers of a CQ, and query entailment is the problem of deciding whether an ontology entails a given Boolean CQ by