Boolean expression simplification Exercise 12 solution 

(a || b) && (!a && !b)
false

The left side says at least 1 of a and b must be true. The right side says both a and b must be false. Both side must be true. This is not possible.

It is also possible to simplify the expression by extracting a not (!) from the right side.

(a || b) && !(a || b)

This is equivalent to c && !c. (See the explanation for Exercise 2.)

Exercise 11 solution
Exercise 13 solution
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