
theorem
  for n be non zero Nat for F be Tuple of n,BOOLEAN st F = 0*n holds
  Absval 'not' F = 2 to_power n - 1
proof
  let n be non zero Nat;
  let F be Tuple of n,BOOLEAN;
  assume
A1: F = 0*n;
  thus Absval 'not' F = - Absval F + 2 to_power n - 1 by BINARI_2:13
    .= - 0 + 2 to_power n - 1 by A1,Th6
    .= 2 to_power n - 1;
end;
