PREFIX vivo: <http://vivoweb.org/ontology/core#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

CONSTRUCT {
    ?advisor vivo:advisorIn ?advisingRelationship .
    ?advisingRelationship vivo:advisor ?advisor
} WHERE {
    ?advisor vivo:advisorIn ?advisingRelationship .
    OPTIONAL {
         ?advisingRelationship vivo:advisor ?advisor
    }
}
