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Consider a university database with relations

student$($sid$,$name$)-$ student and name for each student

course $($cid$,$ title$)-$ course ID and title for each course

passed$($sid$,$ cid$)-$ which courses each student has cleared already

core $($cid$)$ IDs of core courses

Write relational algebra, TRC$,$ DRC expressions and SQL to compute each of the following

relations:

A$)$ IDs of students who have not yet cleared any course.

B$))$ IDs of students who have not yet cleared all core courses.

C$)$ IDs of core courses that are still pending for at least one student.