In many applications, there is an increasing need for the new types of RDF data analysis that are not covered by standard reasoning tasks such as SPARQL query answering. One such important analysis task is entity comparison, i.e., determining what are similarities and differences between two given entities in an RDF graph. For instance, in an RDF graph about drugs, we may want to compare Metamizole and Iboprufen and automatically find out that they are similar in that they are both analgesics but, in contrast to Metamizole, Ibuprofen also has a considerable anti-inflammatory effect. Entity comparison is a widely used functionality available in many information systems, such as universities or product comparison websites. However, comparison is typically domain-specific and depends on a fixed set of aspects to compare. In this paper, we propose a formal framework for domain-independent entity comparison over RDF graphs. We model similarities and differences between entities as SPARQL queries satisfying certain additional properties, and propose algorithms for computing them.
Faceted search is the de facto approach for exploration of data in e-commerce: it allows users to construct queries in an intuitive way without a prior knowledge of formal query languages. This approach has been recently adapted to the context of RDF. Existing faceted search systems however do not allow users to construct queries with aggregation and recursion which poses limitations in practice. In this work we extend faceted search over RDF with these functionalities and study the corresponding query language. In particular, we investigate complexity of the query answering and query containment problems.:Samsung S8
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