The Challenge of Optional Matching in SPARQL
FoIKS, pp. 169-190, 2016.
Conjunctive queries are arguably the most widely used querying mechanism in practice and the most intensively studied one in database theory. Answering a conjunctive query CQ comes down to matching all atoms of the CQ simultaneously into the database. As a consequence, a CQ fails to provide any answer if the pattern described by the query...More
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