Which film producer did M1 , M2 , M3 , and M4 found
SELECT DISTINCT ?x0 WHERE {
?x0 a ns:film.producer .
?x0 ns:organization.organization.founders M1 .
?x0 ns:organization.organization.founders M2 .
?x0 ns:organization.organization.founders M3 .
?x0 ns:organization.organization.founders M4
}