# bound


PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc:   <http://purl.org/dc/elements/1.1/>
PREFIX xsd:   <http://www.w3.org/2001/XMLSchema#>
SELECT ?name
 WHERE { ?x foaf:givenName  ?name .
         OPTIONAL { ?x dc:date ?date } .
         FILTER ( bound(?date) ) }