EXERCISE SET 2
===============

1. Given the suppliers-and-parts database, what is the value of
   S JOIN SP JOIN P?

2. Let R be a relation of degree n. How many different projections
   of R are there?

3. (a) Verify the following claim for the relations A and B: If
   A and B have the same headings, A JOIN B is equivalent to
   A INTERSECT B.
   (b) What other known relation is A JOIN B equivalent to if
   A and B have disjoint headings?

4. Are TIMES and DIVIDEBY inverse operations in relational
   algebra (similar to multiplication and division in arithmetics)?

The remaining exercises are all based on the suppliers-and-parts database:

5. Get full details of all projects.

6. Get full details of all projects in London.

7. Get supplier numbers for suppliers who supply project J1.

8. Get all shipments where quantity is in the range 300 to 750 inclusive.

9. Get all part-color/part-city pairs currently represented in the database.

10. Get part numbers for parts supplied by a supplier in London to a project in London.