1.Explain the statement that relational algebra operators can be com-posed. Why is the ability to compose operators important?
2.Consider the Supplier-Parts-Catalog schema from the previous ques-tion. State what the following queries compute:
1. πsname(πsid((σcolor=red_Parts) ;: (σcost<100Catalog)) ;: Suppliers )
2. πsname(πsid((σcolor=red_Parts) ;: (σcost<100Catalog) ;: Suppliers ))
3. (πsname((σcolor=red_Parts) ;: (σcost<100Catalog) ;: Suppliers )) ∩
(πsname((σcolor=green_ Parts) ;: (σcost<100Catalog) ;: Suppliers ))
4. (πsid((σcolor=red_Parts) ;: (σcost<100Catalog) ;: Suppliers )) ∩
(πsid((σcolor=green_ Parts) ;: (σcost<100Catalog) ;: Suppliers ))
5. πsname((πsid,sname((σcolor=red_Parts) ;: (σcost<100Catalog) ;: Suppliers )) ∩
(πsid,sname((σcolor=green_ Parts) ;: (σcost<100Catalog) ;: Suppliers )))