prefix :     <http://example.org/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix xsd:  <http://www.w3.org/2001/XMLSchema#>
prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

:Researcher {
 rdfs:label  xsd:string       ;
 :birthPlace @:Place        ? ;
 :birthDate  xsd:date       ? ;
 :employer   @:Organization * ;
}
:Place {
    :country @:Country
}
:Organization {
    a [ :Organization ]
}
:Country {
    a [ :Country ]
}
