7 Calculate the mark functions q(x) and r(x) of the solution sets for all equations that are solvable with regard to y, but not uniquely. Check the following equations for uniqueness and solvability with regard to y. Calculate all solution functions y = g(x) and verify them:

x1x3y ∨ x2(x3 ⊕ y) ∨ x1x3y = 1, (4.43)

x1x3y ∨ x2(x3 ⊕ y) ∨ x2y · (x1 ∨ x3) = 1, (4.44)

x2x3y ∨ x2(x3 ⊕ y) ∨ x1x2x3 = 0, (4.45)

x1x2y ∨ x2(x3 ⊕ y) = 0. (4.46)