Rewriting Conjunctive Queries under Description Logic Constraints ( Technical Report )
نویسندگان
چکیده
We consider the problems of conjunctive query answering and rewriting under Description Logic constraints. We present a query rewriting algorithm for ELHI knowledge bases, and use it to show that query answering in this setting is PTime-complete w.r.t. data complexity. We show that our algorithm is worst-case optimal for languages with data complexity of query answering ranging from LogSpace to PTimecomplete.
منابع مشابه
Rewriting Conjunctive Queries under Description Logic Constraints
We consider the problems of conjunctive query answering and rewriting under Description Logic constraints. We present a query rewriting algorithm for ELHI knowledge bases, and use it to show that query answering in this setting is PTime-complete w.r.t. data complexity. We show that our algorithm is worst-case optimal for languages with data complexity of query answering ranging from LogSpace to...
متن کاملTractable 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 (DLs) are constraint languages that have been extensively studied with the goal of providing useful modeling constructs while keeping the query answering prob...
متن کاملFirst Order-Rewritability and Containment of Conjunctive Queries in Horn Description Logics
We study FO-rewritability of conjunctive queries in the presence of ontologies formulated in a description logic between EL and Horn-SHIF , along with related query containment problems. Apart from providing characterizations, we establish complexity results ranging from EXPTIME via NEXPTIME to 2EXPTIME, pointing out several interesting effects. In particular, FO-rewriting is more complex for c...
متن کاملOptimization Properties for Classes of Conjunctive Regular Path Queries
We are interested in the theoretical foundations of the optimization of conjunctive regular path queries (CRPQs). The basic problem here is deciding query containment both in the absence and presence of constraints. Containment without constraints for CRPQs is EXPSPACE-complete, as opposed to only NPcomplete for relational conjunctive queries. Our past experience with implementing similar algor...
متن کامل