Q#1: Consider the following SMV script:

MODULE nand2(in1, in2)

VAR

out: boolean;

ASSIGN

init(out):= TRUE;

next(out):= !(in1 & in2);

MODULE main

VAR

x1:boolean; x2:boolean;

y1:boolean; y2:boolean;

q1:nand2(x1, y1);

q2:nand2(x2, y2);

DEFINE

z := q1.out xor q2.out;

a) Identify and enlist the unreachable state(s). (2)

b) Enlist the reachable states (3)

c) Select and draw 2 reachable states along with their transitions. (5)

Answer According to the Formal Method in Software Engineering Context.