a- Draw the query graph. b- Draw the query tree corresponding to the relational algebra expression. c- Draw the initial query tree, then show how the same query tree is optimized by heuristic rules optimization in another figure. Q 4: SELECT Pnumber, Pname, COUNT () FROM PROJECT, WORKS_ON, EMPLOYEE WHERE Pnumber=Pno AND Ssn=Essn AND Dno=5 GROUP BY Pnumber, Pname