Did M1 , M2 , and M3 employ a person
SELECT count(*) WHERE {
?x0 a ns:people.person .
M1 ns:business.employer.employees/ns:business.employment_tenure.person ?x0 .
M2 ns:business.employer.employees/ns:business.employment_tenure.person ?x0 .
M3 ns:business.employer.employees/ns:business.employment_tenure.person ?x0
}