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

<Ex:$1>
      a       foaf:Person ;
      foaf:mbox "Ex:$2" ;
      foaf:name "Ex:$1" ;
      foaf:officeNumber "Ex:$3" ;
      foaf:supervisor <Ex:$4> .

<Ex:$4>
      a       foaf:Person ;
      foaf:name "Ex:$4" .