Did M4 star a art director employed by M1 and employed by M2 and M3
SELECT count(*) WHERE {
?x0 a ns:film.film_art_director .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
M4 ns:film.film.starring/ns:film.performance.actor ?x0
}