1 Why in both cases the intersection of partial solution sets with the same right side has to be used? Let be given partial solution sets of f(x) = 1, g(x) = 1, f(x) = 0, and g(x) = 0, respectively. Consider the two equations f(x) ∧ g(x) = 1 and f(x) ∨ g(x) = 0.