Q

$A=\{,\}$

B $=\{,\}$

C $=\{,\}$

D $=\{,\}$

B

C

D

Constraint Satisfaction Problems $2(5$ points$)$

Apply the AC$-3$ algorithm on the CSP problem in Figure $1.$ Complete the queue for each

iteration, as well as the values for the variables $($A$,$ B$,$ C$,$ D$).$ The initial queue is provided

with the first constraint underlined, indicating that the respective variables must be

updated. For the queue, use lexicographical sorting. For example, $($A$,$ B$)$ must appear

before $($A$,$ C$)$ in the queue. After the $\text{'}+\text{'}$ sign, you write the constraints that were affected by

the variable updates, and thus are added to the queue in the next iteration. Consider the

constraints in both directions. In other words, for constraint $(A,B),$ consider $(A,B)$ and $(B,A)$

simultaneously, as we have seen in class.

$A=\{,\}$

C $=\{,\}$

$+\{,\}$