Show simple item record

Managing Uncertainty and Ontologies in Databases

dc.contributor.advisorSubrahmanian, V.S.en_US
dc.contributor.authorHung, Edwarden_US
dc.date.accessioned2005-08-03T13:58:12Z
dc.date.available2005-08-03T13:58:12Z
dc.date.issued2005-04-18en_US
dc.identifier.urihttp://hdl.handle.net/1903/2415
dc.description.abstractNowadays a vast amount of data is generated in Extensible Markup Language (XML). However, it is necessary for applications in some domains to store and manipulate uncertain information, e.g. when the sensor inputs are noisy, or we want to store data that is uncertain. Another big change we can see in applications and web data is the increasing use of ontologies to describe the semantics of data, i.e., the semantic relationships between the terms in the databases. As such information is usually absent from traditional databases, there is tremendous opportunity to ask new kinds of queries that could not be handled in the past. This provides new challenges on how to manipulate and maintain such new kinds of database systems. In this dissertation, we will see how we can (i) incorporate and manipulate uncertainty in databases, and (ii) efficiently compute aggregates and maintain views on ontology databases. First, I explain applications that require manipulating uncertain information in XML databases and maintaining web ontology databases written in Resource Description Framework (RDF). I then introduce the probabilistic semistructured PXML data model with two formal semantics. I describe a set of algebraic operations and its efficient implementation. Aggregations of PXML instances are studied with two semantics proposed: possible-worlds semantics and expectation semantics. Efficient algorithms with pruning are given and evaluated to show their feasibility. I introduce PIXML, an interval probability version of PXML, and develop a formal semantics for it. A query language and its operational semantics are given and proved to be sound and complete. Based on XML, RDF is a language used to describe web ontologies. RDQL, an RDF query language, is extended to support view definition and aggregations. Two sets of algorithms are given to maintain non-aggregate and aggregate views. Experimental results show that they are efficient compared with standard relational view maintenance algorithms.en_US
dc.format.extent1275074 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.titleManaging Uncertainty and Ontologies in Databasesen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentComputer Scienceen_US
dc.subject.pqcontrolledComputer Scienceen_US
dc.subject.pquncontrolleduncertaintyen_US
dc.subject.pquncontrolledontologyen_US
dc.subject.pquncontrolledprobabilistic semistructured databaseen_US
dc.subject.pquncontrolledaggregate view maintenanceen_US
dc.subject.pquncontrolledXMLen_US
dc.subject.pquncontrolledRDFen_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record