Was a writer of M0 , M1 , and M2 employed by M3 and M4 , employed by M5 , and employed by M6
SELECT count(*) WHERE {
?x0 ns:film.writer.film M0 .
?x0 ns:film.writer.film M1 .
?x0 ns:film.writer.film M2 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M4 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M5 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M6
}