Chapter 6, Problem 5E

Explanation of Solution

Solving cryptarithmetic problem:

a. Choose the X3 variable. Its domain is{0,1}.

b. Choose the value 1 for X3. (The user can’t choose 0; it wouldn’t survive forward checking, because it would force F to be 0, and the leading digit of the sum must be non-zero.)

c. Choose F, because it has only one remaining value.

d. Choose the value 1 for F.

e. Now X2 and X1 are tied for minimum remaining values at 2; let’s choose X2.

f. Either value survives forward checking; let’s choose 0 for X2.

g. Now X1 has the minimum remaining values.

h. Again, arbitrarily choose 0 for the value of X1...