Was M3 a company whose founder was employed by M0 , M1 , and M2
SELECT count(*) WHERE {
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M0 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
M3 a ns:business.employer .
M3 ns:organization.organization.founders ?x0
}