Was a actor employed by M1 , employed by M2 , and employed by a employer of M3
SELECT count(*) WHERE {
?x0 a ns:film.actor .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company ?x1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
?x1 ns:business.employer.employees/ns:business.employment_tenure.person M3
}