sub is_ok
{
    my ($x, $y) = @_;
    my (%x, %y);

    @x{@$x} = 1;
    @y{@$y} = 1;

    foreach my $k (keys %x)
    {
        return 0 if exists $y{$k};
    }

    return 1;
}
[download]

1. This will work with groups of arbitrary size and will also work with groups of different sizes.
2. It will also work with groups that contain arbitrary data.
3. It will throw warnings if any of the elements are undef.
4. It does string comparisons, so 2, 4, 6 and 1.0, 2.0, 3.0 may or may not be ok. I will leave numeric comparisons as an exercise for the reader.

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.