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 "incoming" contacts (people who say they know the person in
# question) to propose these contacts as new acquaintances.

SELECT DISTINCT ?result WHERE
{
	?result foaf:knows <PERSON> .

	OPTIONAL
	{
		?result foaf:knows ?var1 .
		FILTER ( <PERSON> = ?var1 )
		<PERSON> foaf:knows ?result .
	}
	FILTER ( !bound(?var1) )
}