question: Which film producer did M1 and M2 star , M3 star , M4 star , and M5 and M6 star
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:film.actor.film/ns:film.performance.film M1 .
  ?x0 ns:film.actor.film/ns:film.performance.film M2 .
  ?x0 ns:film.actor.film/ns:film.performance.film M3 .
  ?x0 ns:film.actor.film/ns:film.performance.film M4 .
  ?x0 ns:film.actor.film/ns:film.performance.film M5 .
  ?x0 ns:film.actor.film/ns:film.performance.film M6
  }