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|Abstract=Rules and ontologies can be used to enrich a database system with advanced data access capabilities. The success of this paradigm has led to a number of languages such as DL-Lite, Datalog+/- and OWL RL. The two major approaches to answering queries under constraints expressed in such languages are forward-chaining (materialization) and backward-chaining (query rewriting). The latter is typically focused on first-order queries that have only limited expressivity. We propose a querying formalism based on monadic second-order logic which subsumes and goes beyond conjunctive queries and regular path queries, but still has a decidable query subsumption problem. We devise methods for rewriting rule sets to queries in this new formalism and we show that query entailment in most of the established rule-based approaches can be decided by combining two methods: (i) bottom-up forward-chaining computation w.r.t. a rule set with the bounded treewidth model property and (ii) top-down second-order query rewriting w.r.t. a rewritable rule set. | |Abstract=Rules and ontologies can be used to enrich a database system with advanced data access capabilities. The success of this paradigm has led to a number of languages such as DL-Lite, Datalog+/- and OWL RL. The two major approaches to answering queries under constraints expressed in such languages are forward-chaining (materialization) and backward-chaining (query rewriting). The latter is typically focused on first-order queries that have only limited expressivity. We propose a querying formalism based on monadic second-order logic which subsumes and goes beyond conjunctive queries and regular path queries, but still has a decidable query subsumption problem. We devise methods for rewriting rule sets to queries in this new formalism and we show that query entailment in most of the established rule-based approaches can be decided by combining two methods: (i) bottom-up forward-chaining computation w.r.t. a rule set with the bounded treewidth model property and (ii) top-down second-order query rewriting w.r.t. a rewritable rule set. | ||
− | |Download= | + | |Download=KroetzschRudolph MSO-Queries 2011.pdf, |
|Projekt=ExpresST | |Projekt=ExpresST | ||
|Forschungsgruppe=Wissensmanagement | |Forschungsgruppe=Wissensmanagement |
Aktuelle Version vom 1. Dezember 2011, 16:18 Uhr
Published: 2011
November
Type: Technical Report
Institution: Institut AIFB, KIT
Erscheinungsort / Ort: Karlsruhe
Archivierungsnummer:3019
Kurzfassung
Rules and ontologies can be used to enrich a database system with advanced data access capabilities. The success of this paradigm has led to a number of languages such as DL-Lite, Datalog+/- and OWL RL. The two major approaches to answering queries under constraints expressed in such languages are forward-chaining (materialization) and backward-chaining (query rewriting). The latter is typically focused on first-order queries that have only limited expressivity. We propose a querying formalism based on monadic second-order logic which subsumes and goes beyond conjunctive queries and regular path queries, but still has a decidable query subsumption problem. We devise methods for rewriting rule sets to queries in this new formalism and we show that query entailment in most of the established rule-based approaches can be decided by combining two methods: (i) bottom-up forward-chaining computation w.r.t. a rule set with the bounded treewidth model property and (ii) top-down second-order query rewriting w.r.t. a rewritable rule set.
Download: Media:KroetzschRudolph MSO-Queries 2011.pdf
Semantische Technologien, Informationssysteme, Deduktive Datenbanken, Logik