UCQ-rewritings for disjunctive knowledge and queries with negated atoms

Matos Alfonso, Enrique

dc.contributor.author	Matos Alfonso, Enrique	el
dc.date.accessioned	2024-08-30T06:11:51Z
dc.date.available	2024-08-30T06:11:51Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/60046
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.27742
dc.rights	Αναφορά Δημιουργού 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by/3.0/gr/	*
dc.subject	Disjunctive existential rules	en
dc.subject	QQuery rewriting	el
dc.subject	Backward chaining	el
dc.title	UCQ-rewritings for disjunctive knowledge and queries with negated atoms	en
dc.contributor.department	Εργαστήριο Συστημάτων Τεχνητής Νοημοσύνης και Μάθησης	el
heal.type	doctoralThesis
heal.classification	Computer Science	en
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2024-05-14
heal.abstract	In this thesis, the problem of query rewriting for conjunctive queries with negation with respect to disjunctive existential rules is studied. Query rewriting is a well-known approach for query answering on knowledge bases with incomplete data. Three rewriting techniques are proposed that find -rewritings for queries with negation on the (disjunctive) existential rules framework. The first technique uses resolution with respect to constraints in order to eliminate the negated atoms from the input query. A set of conjunctive queries is produced and it can be rewritten with the existential rules in the knowledge base producing more -rewritings. The second technique focuses on finding a -rewriting of queries with not more than one negated atom. Such queries are transformed into existential rules and the constraints or the knowledge base are rewritten. The method keeps track of the rewritings produced by the rule corresponding to the transformed query and yields a complete -rewriting. The third rewriting technique uses constraints and conjunctive queries to remove the disjunctive components of disjunctive existential rules. This process eventually generates new non-disjunctive rules, i.e., existential rules. The generated rules can then be used to produce new rewritings using existing rewriting approaches for existential rules. With the proposed technique we are able to provide complete -rewritings for union of conjunctive queries with universally quantified negation. The proposed techniques are implemented in the COMPLETO system (v1, v2, and v3 respectively) and some experiments were carried out to evaluate the viability of the proposed solutions. We also address the undecidability of the existence of a finite and complete -rewriting and the identification of finite unification sets (fus) of rules. We introduce new rule classes, connected linear rules and connected domain restricted rules, that exhibit the fus property for existential rules. Additionally, we propose disconnected disjunction for disjunctive existential rules to achieve the fus property when we extend the introduced rule fragments to disjunctive existential rules. Finally, we present ECOMPLETO, a version of our system implemented in Elixir programming language, capable of handling ¬ s with universally quantified negation and disjunctive existential rules. Our experiments demonstrate ECOMPLETO’s consistent ability to produce finite -rewritings, and describe the performance on different ontologies and queries.	en
heal.advisorName	Στάμου, Γεώργιος	el
heal.committeeMemberName	Κόλλιας, Στέφανος	el
heal.committeeMemberName	Σταφυλοπάτης, Ανδρέας-Γεώργιος	el
heal.committeeMemberName	Φωτάκης, Δημήτριος	el
heal.committeeMemberName	Κουμπαράκης, Εμμανουήλ	el
heal.committeeMemberName	Βουλόδημος, Αθανάσιος	el
heal.committeeMemberName	Παγουρτζής, Αριστείδης	el
heal.committeeMemberName	Στάμου, Γεώργιος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ηλεκτρολόγων Μηχανικών και Μηχανικών Υπολογιστών. Τομέας Τεχνολογίας Πληροφορικής και Υπολογιστών. Εργαστήριο Συστημάτων Τεχνητής Νοημοσύνης και Μάθησης	el
heal.academicPublisherID	ntua
heal.numberOfPages	110 σ.	el
heal.fullTextAvailability	false