theorem
  A |^ (0, 2) = {<%>E} \/ A \/ (A ^^ A)
proof
  thus A |^ (0, 2) = A |^ (0, 1) \/ A |^ (1 + 1) by Th26
    .= {<%>E} \/ A \/ A |^ (1 + 1) by Th46
    .= {<%>E} \/ A \/ (A ^^ A) by FLANG_1:26;
end;
