sub common_subset
  {
    my $a = shift;
    @_ or return @$a;
    my %h;
    @h{@$a} = ();
    grep { exists $h{$_} } common_subset( @_ )
  }


##</code><code>##

  my @sets =
  (
    [ 0, 1, 2, 3,          7, 8, 9, 10, 11, 12, 13, 14, 15,     ],
    [ 0,       3,          7, 8,    10, 11,     13, 14,     16, ],
    [ 0, 1, 2, 3,    5,    7, 8,    10, 11, 12, 13, 14,     16, ],
    [       2, 3, 4,    6, 7, 8,    10, 11, 12,     14,     16, ],
    [ 0, 1, 2, 3,          7, 8, 9, 10, 11,     13, 14, 15,     ],
  );

  my @l = common_subset( @sets );