ASK WHERE {
	<http://www.example.org/#me> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> .
	<http://www.example.org/#me> <http://xmlns.com/foaf/0.1/knows> ?a .
	?a <http://xmlns.com/foaf/0.1/name> "John Doe" .
	FILTER isBlank(?a)
}