RELATIONAL ALGEBRA - Please DO NOT answer in SQL

I want to double check if my answers are correct

Consider the following relation schemas. The primary keys are underlined. Students(sID, sName, sDepartment, sDegree: integer, advisorID) Lectures(lID, lName, lDepartment, lDegree: integer, pID) Register(sID, lID, score: integer) Professors(pID, name) All attributes are strings if not indicated otherwise.

1. Find the names of students who register for every lecture of the Engineering department.

2. Find the names of students whose department is Engineering.

3. Find the names of students who got the highest score in the DBMS lecture.

4. Display the student names, lecture names, and scores of all those students who register for a higher degree lecture than their degree is.

5. Find the names of professors who do not take any lecture and do not have any advisee.

6. Find the names of students who registered for their advisors lecture and got less than 50 on scores.