Prove ou refute que, sendo A,B e C subconjuntos arbitrários de X, se verificam as seguintes propriedades: (a) A− (B − C) = (A−B)− C (b) (A ∩B)− C = A ∩ (B − C) (c) (A ∪B)− C = A ∪ (B − C) (d)(A−B)c = Ac −Bc; (e) A ∪ (B −A) = A ∪B (f) A ∩ (B ∪ C) = (A ∩B) ∪ C (g) A−B = A ∩Bc; (h) A ∪B = A ∪ (B ∩ C) se e só se B ⊆ C (i) (A−B)× C = (A× C)− (B × C) (j) (A ∪B)× C = (A× C) ∪ (B × C) (l) (A ∩B)× C = (A× C) ∩ (B × C).