Express each of the following queries in relational algebra

- Be sure that the resulting relation lists just the attributes that are given in the instruction. - Do not include unnecessary relations in your queries.

4. Find the course id of all courses offered in Spring 2022. (5 points) 5. Find the name of all instructors in Computer Science department with salary more than $80,000. (5 points) 6. Find the IDs of all instructors who have taught or are teaching a course from a different department than the one to which they are assigned. For example, the result would include Electrical Engineering professors who teach Computer Science courses. (5 points)

Consider the Schema diagram for a university database shown in Figure 2.8 on page 47 of the textbook