![ata chapter iff ata chapter iff](https://slidetodoc.com/presentation_image_h/9c726b5d4884efcd4a2476db9ff833ce/image-11.jpg)
In the next section, we show that incorporating the content of RDF data may provide stronger inferences about query completeness. One fundamental limitation of this work is that the completeness check is agnostic of the content of the RDF data to which the completeness information is given, which results in weaker inferences. In previous work, Darari et al. proposed a framework to describe completeness of RDF data and check query completeness based on completeness information. Such a check is called completeness entailment. Motivated by the above rationales, we argue that it is important to describe completeness of RDF data and provide a technique to check query completeness based on RDF data with its completeness information. Consequently, a user asking for the children of Apollo 11 crew should obtain not only query answers, but also the information that the answers are complete. To illustrate, suppose that in addition to the complete data of Apollo 11 crew, Wikidata is also complete for the children of the three astronauts. Nevertheless, the availability of explicit completeness information can benefit data access over RDF data sources, commonly done via SPARQL queries. Wikidata is actually complete for all the Apollo 11 crew We verify the applicability of our framework using Wikidata and develop COOL-WD, a completeness tool for Wikidata, used to annotate Wikidata with completeness statements and reason about the completeness of query answers over Wikidata. We then identify a practically relevant fragment of completeness information, suitable for crowdsourced, entity-centric RDF data sources such as Wikidata, for which we develop an indexing technique that allows to scale completeness reasoning to Wikidata-scale data sources. In this paper we develop a technique to check query completeness based on RDF data annotated with completeness information, taking into account data-specific inferences that lead to an inference problem which is \(\varPi ^P_2\)-complete.
![ata chapter iff ata chapter iff](https://static.docsity.com/documents_first_pages/notas/2010/08/29/61628d616963d7b38ffe13134d0d14f1.png)
While the Semantic Web is generally incomplete by nature, on certain topics, it already contains complete information and thus, queries may return all answers that exist in reality. Nowadays, more and more RDF data is becoming available on the Semantic Web.