Week 8 Answers

1. Consider the following statements:
   S1: All normal-forms are defined using functional dependencies.
   S2: Normalization is a top-down process to deal with redundancy in data representation. Choose the correct option:a. S1: True; S2: True
   b. S1: True; S2: False
   c. S1: False; S2: False
   d. S1: False; S2: True

Answer: C

2. Fill in the blanks:
   S1: An attribute of a relation schema R is called a prime-attribute of R if it is a member of some _ _ _ _ _ of R.
   S2: An attribute of a relation schema R is called a non-prime-attribute of R if it is NOT a member of any _ _ _ _ of R
   a. S1: Candidate-key; S2: Candidate-key
   b. S1: Candidate-key; S2: Super-key
   c. S1: Super-key; S2: Candidate-key
   d. S1: Super-key; S2: Super-keyAnswer: A

3. Consider a relation R(A, B, C, D, E, F, G) and the following FDs:
   {AB → CD, AF → D, DE → F, C → G, F → E, G → A}. Find out {C​ , F }+:
   a. {C, F}
   b. {C, F, G, E}
   c. {C, F, G, E, A}
   d. {C, F, G, E, A, D}Answer: D

4. Consider a relation R(A, B, C, D, E, F) and the given FDs:
   {AB → C, C → D, B → E, DE → F, F → AB}. Choose the incorrect option:
   a. AB is a candidate key of R
   b. F is a candidate key of R
   c. BC is a candidate key of R
   d. CD is a candidate key of RAnswer: C

5. Consider a relation R(part_no, part_description, part_price, supplier_id, supplier_address).
   The following FDs hold on R:

• part_no → part_description
• supplier_id → supplier_address
• {part_no, supplier_id} → part_price Find the candidate key of relation R:
  a. part_no
  b. supplier_id
  c. {supplier_id, part_no}
  d. None of the aboveAnswer: C

6. Consider the relation given in Question 5, and find out which of the following statement is TRUE about R:
   a. R is in 1NF only
   b. R is in 2NF but not in 3NF
   c. R is in 3NF but not in BCNF
   d. R is in BCNFAnswer: C

7. Consider the following statements:
   S1: A relation in which every key contains only one attribute is in 2NF.
   S2: In a 3NF relation, a non-key attribute may be transitively dependent on the primary key. Choose the correct option:
   a. S1: True; S2: True
   b. S1: False; S2: True
   c. S1: False; S2: False
   d. S1: True; S2: FalseAnswer: D

8. Consider a relation R(A, B, C, D, E, F, G) and the FD set:
   F1 = {B → ACD, DE → F, F → D, E → FGB, BCG → CE, EG → CD}. Let F’ be a minimal cover of F1. Find out the incorrect statement about F’:
   a. F’ contains F → D
   b. F’ does not contain DE → F
   c. F’ does not contain EG → CD
   d. F’ does not contain BG → EAnswer: D

9. Consider a relation R(A, B, C, D, E, F) and the FD set given below:
   F1 = { AB → C, B → D, D → E, AE → F, C → A } Choose the correct option:
   a. R is in 2NF, but not in 3NF
   b. R is not in 2NF
   c. R is in 3NF, but not in BCNF
   d. R is in BCNFAnswer: A

10. Consider the decomposition of a relation R(A, B, C) into two relations R1(A, B) and R2(B, C) and the given instances of R, R1, and R2. Suppose FD set for R is :{B → A, B → C}. What is TRUE with respect to the decomposition:
    a. Lossy; Dependency preserving
    b. Lossless; Dependency preserving
    c. Lossy; Not Dependency preserving
    d. Lossless; Not Dependency preservingAnswer: B