(i) Let Ai ( (i, i = 1, 2,..., n, and set E = A1 × ... × An. Then E = ( if and only if at least one of Ai, i = 1, 2, ..., n, is = (.
(ii) If also Bi ( (i, i = 1, 2, ..., n, and F = B1 × ... × Bn. Then show that E ( F = (A1 ×...× An) ( (B1 ×...× Bn) = (A1 ( B1) × ... × (An ( Bn).