use strict;
use warnings;
use Algorithm::Combinatorics qw(combinations variations_with_repetition);

my @data = ('A', 'B', 'C', 'D', 'E', 'F');
my $cardinality = 2;


for my $cardinality (1..3) {

    print "\n\nCardinality: $cardinality\n";

    my $dataref = getPairsOfCombinations(\@data, $cardinality);

    if ($dataref == 0) {
        die "Bad return\n";
    }

    for (my $i = 0; $i < scalar(@$dataref); $i++) {

        print "( " .  join( ',', map {  "( " . join(',', @{$_}) . " )"  }   @{ $dataref->[$i] }  ) .  " )\n";

    }
}

exit(0);


sub getPairsOfCombinations {
    my ($data, $cardinality) = @_;

    my @combinations = combinations(\@data, $cardinality);
    my @variations = variations_with_repetition([0..$#combinations], 2);

    return [ map { [ map { $combinations[$_] } @{$_} ] } @variations ];
}

##</code><code>##


Cardinality: 1
( ( A ),( A ) )
( ( A ),( B ) )
( ( A ),( C ) )
( ( A ),( D ) )
( ( A ),( E ) )
( ( A ),( F ) )
( ( B ),( A ) )
( ( B ),( B ) )
( ( B ),( C ) )
( ( B ),( D ) )
( ( B ),( E ) )
( ( B ),( F ) )
( ( C ),( A ) )
( ( C ),( B ) )
( ( C ),( C ) )
( ( C ),( D ) )
( ( C ),( E ) )
( ( C ),( F ) )
( ( D ),( A ) )
( ( D ),( B ) )
( ( D ),( C ) )
( ( D ),( D ) )
( ( D ),( E ) )
( ( D ),( F ) )
( ( E ),( A ) )
( ( E ),( B ) )
( ( E ),( C ) )
( ( E ),( D ) )
( ( E ),( E ) )
( ( E ),( F ) )
( ( F ),( A ) )
( ( F ),( B ) )
( ( F ),( C ) )
( ( F ),( D ) )
( ( F ),( E ) )
( ( F ),( F ) )


Cardinality: 2
( ( A,B ),( A,B ) )
( ( A,B ),( A,C ) )
( ( A,B ),( A,D ) )
( ( A,B ),( A,E ) )
( ( A,B ),( A,F ) )
( ( A,B ),( B,C ) )
( ( A,B ),( B,D ) )
( ( A,B ),( B,E ) )
( ( A,B ),( B,F ) )
( ( A,B ),( C,D ) )
( ( A,B ),( C,E ) )
( ( A,B ),( C,F ) )
( ( A,B ),( D,E ) )
( ( A,B ),( D,F ) )
( ( A,B ),( E,F ) )
( ( A,C ),( A,B ) )
( ( A,C ),( A,C ) )
( ( A,C ),( A,D ) )
( ( A,C ),( A,E ) )
( ( A,C ),( A,F ) )
( ( A,C ),( B,C ) )
( ( A,C ),( B,D ) )
( ( A,C ),( B,E ) )
( ( A,C ),( B,F ) )
( ( A,C ),( C,D ) )
( ( A,C ),( C,E ) )
( ( A,C ),( C,F ) )
( ( A,C ),( D,E ) )
( ( A,C ),( D,F ) )
( ( A,C ),( E,F ) )
( ( A,D ),( A,B ) )
( ( A,D ),( A,C ) )
( ( A,D ),( A,D ) )
...

Cardinality: 3
( ( A,B,C ),( A,B,C ) )
( ( A,B,C ),( A,B,D ) )
( ( A,B,C ),( A,B,E ) )
( ( A,B,C ),( A,B,F ) )
( ( A,B,C ),( A,C,D ) )
( ( A,B,C ),( A,C,E ) )
( ( A,B,C ),( A,C,F ) )
( ( A,B,C ),( A,D,E ) )
( ( A,B,C ),( A,D,F ) )
( ( A,B,C ),( A,E,F ) )
( ( A,B,C ),( B,C,D ) )
( ( A,B,C ),( B,C,E ) )
( ( A,B,C ),( B,C,F ) )
( ( A,B,C ),( B,D,E ) )
( ( A,B,C ),( B,D,F ) )
( ( A,B,C ),( B,E,F ) )
( ( A,B,C ),( C,D,E ) )
( ( A,B,C ),( C,D,F ) )
( ( A,B,C ),( C,E,F ) )
( ( A,B,C ),( D,E,F ) )
( ( A,B,D ),( A,B,C ) )
( ( A,B,D ),( A,B,D ) )
( ( A,B,D ),( A,B,E ) )
( ( A,B,D ),( A,B,F ) )
( ( A,B,D ),( A,C,D ) )
( ( A,B,D ),( A,C,E ) )
( ( A,B,D ),( A,C,F ) )
( ( A,B,D ),( A,D,E ) )
( ( A,B,D ),( A,D,F ) )
( ( A,B,D ),( A,E,F ) )
( ( A,B,D ),( B,C,D ) )
( ( A,B,D ),( B,C,E ) )
( ( A,B,D ),( B,C,F ) )
( ( A,B,D ),( B,D,E ) )
( ( A,B,D ),( B,D,F ) )
( ( A,B,D ),( B,E,F ) )
( ( A,B,D ),( C,D,E ) )
( ( A,B,D ),( C,D,F ) )
( ( A,B,D ),( C,E,F ) )
( ( A,B,D ),( D,E,F ) )
( ( A,B,E ),( A,B,C ) )
( ( A,B,E ),( A,B,D ) )
( ( A,B,E ),( A,B,E ) )
( ( A,B,E ),( A,B,F ) )
( ( A,B,E ),( A,C,D ) )
( ( A,B,E ),( A,C,E ) )
( ( A,B,E ),( A,C,F ) )
( ( A,B,E ),( A,D,E ) )
( ( A,B,E ),( A,D,F ) )
( ( A,B,E ),( A,E,F ) )
( ( A,B,E ),( B,C,D ) )
( ( A,B,E ),( B,C,E ) )
( ( A,B,E ),( B,C,F ) )
( ( A,B,E ),( B,D,E ) )
( ( A,B,E ),( B,D,F ) )
( ( A,B,E ),( B,E,F ) )
( ( A,B,E ),( C,D,E ) )
( ( A,B,E ),( C,D,F ) )
( ( A,B,E ),( C,E,F ) )
( ( A,B,E ),( D,E,F ) )
( ( A,B,F ),( A,B,C ) )
( ( A,B,F ),( A,B,D ) )
( ( A,B,F ),( A,B,E ) )
( ( A,B,F ),( A,B,F ) )
( ( A,B,F ),( A,C,D ) )
( ( A,B,F ),( A,C,E ) )
( ( A,B,F ),( A,C,F ) )
( ( A,B,F ),( A,D,E ) )
( ( A,B,F ),( A,D,F ) )
( ( A,B,F ),( A,E,F ) )
( ( A,B,F ),( B,C,D ) )
( ( A,B,F ),( B,C,E ) )
( ( A,B,F ),( B,C,F ) )
( ( A,B,F ),( B,D,E ) )
( ( A,B,F ),( B,D,F ) )
( ( A,B,F ),( B,E,F ) )
( ( A,B,F ),( C,D,E ) )
( ( A,B,F ),( C,D,F ) )
( ( A,B,F ),( C,E,F ) )
( ( A,B,F ),( D,E,F ) )
...