Did M3 employ M4 and employ a person that M1 and M2 were written by
SELECT count(*) WHERE {
?x0 a ns:people.person .
?x0 ns:film.writer.film M1 .
?x0 ns:film.writer.film M2 .
M3 ns:business.employer.employees/ns:business.employment_tenure.person ?x0 .
M3 ns:business.employer.employees/ns:business.employment_tenure.person M4
}