my @a = ( 1, 2, 3, 4, 5, 6 );
my @b = ( 3, 4, 5, 6, 7, 8 );
my %a_lookup;
@a_lookup{@a} = ();
my @b_only = grep { not exists $a_lookup{$_} } @b;
print "@b_only\n";


##</code><code>##

use Quantum::Superpositions;

my @a = ( 1 .. 6 );
my @b = ( 3 .. 8 );
print "$_\n" foreach eigenstates( any( @b ) != all( @a ) );