Did a company that was founded by and employed M1 employ M2 and M3
SELECT count(*) WHERE {
?x0 a ns:business.employer .
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M2 .
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M3 .
?x0 ns:organization.organization.founders M1
}