Name
Address
Type (University, High school, Secondary School, Primary School)
Name *
DOB * (>=18)
Has many schools
Name *
DOB * (>=20)
Years of Experience * (>=0)
John and Alex are students in the same school, Robert is a worker. The system must be provide these functions:
john.name
john.age
robert.years_of_exp
john.schoolmates should include alex
Note: (*) is compulsory.