theorem Th46:
  A |^ (0, 1) = {<%>E} \/ A
proof
  thus A |^ (0, 1) = A |^ 0 \/ A |^ (0 + 1) by Th28
    .= {<%>E} \/ A |^ 1 by FLANG_1:24
    .= {<%>E} \/ A by FLANG_1:25;
end;
