UNIVERSITY SCHEMA:

classroom(building, room_number, capacity)

department(dept_name, building, budget)

course(course_id, title, dept_name, credits)

instructor(ID, name, dept_name, salary)

section(course_id, sec_id, semester, year, building, room_number, time_slot_id)

teaches(ID, course_id, sec_id, semester, year)

student(ID, name, dept_name, tot_cred)

takes(ID, course_id, sec_id, year, grade)

advisor(s_ID, i_ID)

time_slot(time_slot_id, day, start_time, end_time)

prereq(course_id, prereq_id)

Write the following query in relational algebra using the university schema:

1. Find the IDs of all students who were taught by an instructor named Einstein; make sure there are no duplicates in the result.