reserve n for non zero Nat,
  j,k,l,m for Nat,
  g,h,i for Integer;

theorem
  for z be Tuple of 1,BOOLEAN st z=<*FALSE*> holds Intval(z) = 0
proof
  let z be Tuple of 1,BOOLEAN such that
A1: z = <*FALSE*>;
  len z = 1 by CARD_1:def 7;
  then z/.1 = z.1 by FINSEQ_4:15
    .= FALSE by A1;
  then Intval(z) = Absval(z) by BINARI_2:def 3;
  hence thesis by A1,BINARITH:15;
end;
