PREFIX : <http://example/> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> SELECT ?nx ?ny ?sx ?sy { ?x foaf:knows ?y. ?x foaf:givenName ?nx. ?y foaf:givenName ?ny. ?x foaf:salary ?sx. ?y foaf:salary ?sy. FILTER(?sx < ?sy && abs(?sx - ?sy) < "3000"^^xsd:integer) }