Relational Algebra

An excellent question for testing your understanding of the relation algebra operations follows:
Assume that R and S are relations containing nR and nS tuples, respectively, and that the relation R includes an attribute A.
What is the maximum and minimum number of tuples that can possibly be in the result of each of the following expressions?

(You can assume appropriate union compatibilities, where needed.)


1- πA(R) project
2- σA>0(R) select
3- R ∪ S union
4- R ∩ S intersection
5- R - S difference
6- R × S product, Cartesian
7- R |X| S join, natural
8- R / S divide

Within your group topic forum, discuss what the appropriate answers to each of these may be.

It is suggested that each of you tackle only 3 or 4 of these, so that no one person ends up doing all the work.