PREFIX ns1: <http://namespace1.org/>
PREFIX ns4: <http://namespace4.org/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl:  <http://www.w3.org/2002/07/owl#>

SELECT ?person ?name ?publication WHERE {
 ?person rdf:type foaf:Person .
 ?person foaf:name ?name .
 OPTIONAL {
   ?author owl:sameAs ?person . 
   ?publication ns4:hasAuthor ?author . 
 }
}