PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl:  <http://www.w3.org/2002/07/owl#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

# discover two distinct "incoming" contacts for acquaintances of the person in
# question to propose these potential 2nd degree acquaintances contacts as new
# acquaintances
SELECT DISTINCT ?result WHERE
{
	<PERSON> foaf:knows ?p1 .
	<PERSON> foaf:knows ?p2 .
	FILTER ( ?p1 != ?p2 )

	?result foaf:knows ?p1 .
	FILTER ( <PERSON> != ?result )
	?result foaf:knows ?p2 .

	OPTIONAL {
		<PERSON> ?knows ?result .
		FILTER ( ?knows = foaf:knows )
	}
	FILTER ( !bound(?knows) )
}