Homework 2
CS422, Summer 2006

Due: Thursday, July 20

Please upload your solutions using CSNS. Note that file uploading will be disabled automatically after 11:59PM of the due date, so please turn in your work on time.

[Reading]

[Exercises]

1. (10pt) Figure 2.15 in the textbook shows a 4-way relationship about Births. Assume that a mother can give birth to more than one baby (e.g. twins), and there could be more than one doctor and/or nurse present at the birth, discuss why the 4-way relationship is a bad design.

2. (20pt) Exercise 3.6.1 (d) (f)

3. (20pt) For each of the following relations, identify all 4NF violations, and decompose the relation into a collection of relations in 4NF.

(a) R(A, B, C, D) with MVD's AB ->-> C and AB ->-> D
(b) R(A, B, C, D, E) with MVD's A ->-> D and  AB ->-> E and FD's B -> D and AB -> C

4. (20pt) For a relation R(A, B, C, D), prove or give a counter-example of the following:

(a) If AB ->-> BC, then AB ->-> B and AB ->-> C
(b) If A ->-> BC, then A ->-> B and A ->-> C

5. (20pt) Exercise 5.2.4 (c) (d) (h) (i)

6. (20pt) Exercise 5.5.2 (a) (b) (c) (d)