Program(_name_, abbreviation)

Department(_name_, abbreviation)
    UNIQUE abbreviation

Hosts(_department_, _program_)
    department -> Department.name
    program -> Program.name

Student(_ssn_, name, login, program)
    program -> Program.name
    UNIQUE login
    UNIQUE (ssn, program)

Branch(_name_, _program_)
    program -> Program.name

BelongsTo(_student_, branch, program)
    student -> Student.ssn
    (student, program) -> Student.(ssn, program)
    (branch, program) -> Branch.(name, program)

Course(_code_, name, credits, department)
    department -> Department.name

Prerequisite(_course_, _prerequisite_)
    course -> Course.code
    prerequisite -> Course.code

Classification(_name_)

Classified(_course_, _classification_)
    course -> Course.code
    classification -> Classification.name

MandatoryProgram(_course_, _program_)
    course -> Course.code
    program -> Program.name

MandatoryBranch(_course_, _branch_, _program_)
    course -> Course.code
    (branch, program) -> Branch.(name, program)

RecommendedBranch(_course_, _branch_, _program_)
    course -> Course.code
    (branch, program) -> Branch.(name, program)

Registered(_student_, _course_)
    student -> Student.ssn
    course -> Course.code

Taken(_student_, _course_, grade)
    student -> Student.ssn
    course -> Course.code

LimitedCourse(_code_, seats)
    code -> Course.code

WaitingList(_student_, _course_, position)
    student -> Student.ssn
    course -> LimitedCourse.code
    UNIQUE (position, course)