! Exercise 3.2.4: Show that each of the following are not valid rules about FD's by giving example relations that satisfy the given FD's (following the “if”) but not the FD that allegedly follows (after the "then”). a) If A → B then B → A. b) If AB → C and A → C, then B → C. c) If AB → C, then A → C or B → C.

Define the following predicates: • A(x) : x is on the board of directors." • E(x) : x earns more than $100, 000. • W(x) : x works more than 60 hours per week. The domain is the set of all employees of a certain company. Match each English statement with its equivalent logical expression. ? v 1. Everyone who works more than 60 hours per week earns more than $100,000. A. 3x(E(x) ^ ¬W(x)) B. Vx(W(x) → E(x)) C. Ex(¬A(x) → E(x)) D. Vx(W(x) ^ E(x)) E. 3x(¬A(x) ^ E(x)) F. 3x(A(x) ^ ¬E(x)^ W(x)) G. Ex(A(x) V ¬E(x) V W(x)) H. Vx(A(x) → E(x)) I. Vx(A(x) ^ E(x)) 2 v 2. Someone on the board of directors does not earn more that $100.000 and works more than 60 hours per week. ? v 3. Every member of the board of directors earns more than $100,000. 2. v 4. There is someone who is not on the board of directors and earns more than $100,000. ? v 5. There is someone who earns more than $100,000, but does not work more than 60 hours per week.

Please refer to the following diagram for Q19 to Q20. PERSON PK P_ID P_LNAME P_FNAME EMPLOYEE P_ID EMP_HIRE_DATE STUDENT P ID STUDY_MAJOR PK, FK1 PK, FK1

How is the relation of class A and class B best described from the code snippet below? public class A {private B b = new B();public A() {}} Group of answer choices Aggregation Inheritance Composition Delegation