Tractable query answering and rewriting under description logic constraints

Answering queries over an incomplete database w.r.t. a set of constraints is an important computational task with applications in fields as diverse as information integration and metadata management in the Semantic Web. Description Logics (DL) are constraint languages that have been extensively studied in the past with the goal of providing useful modeling constructs while keeping the query answering problem decidable. For many DLs, query answering under constraints can be reduced to query rewriting: given a conjunctive query Q and a set of DL constraints T , the query Q can be transformed into a datalog query QT that takes into account the semantic consequences of T ; then, to obtain answers to Q w.r.t. T and some (arbitrary) database instance A, one can simply evaluate QT over A using existing (deductive) database technology, without taking T into account. In this paper, we present a novel query rewriting algorithm that handles constraints modeled in the DL ELHIO¬ and use it to sho...

• Type: Journal
• Year: 2010
• Where: JAPLL
• Authors: Héctor Pérez-Urbina, Boris Motik, Ian Horrocks
• Keywords: Data Complexity, Datalog Query Qt, Description Logics, JAPLL 2010