PREFIX  rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX  foaf:   <http://xmlns.com/foaf/0.1/> 

SELECT ?person ?name 
WHERE 
{
    ?person rdf:type  foaf:Person .
    ?person foaf:knows/foaf:name | foaf:firstName ?name .
    
}
