# One pairwise intersection:
# $intrx1_2 is a bit vector whose bits correspond to the positions
# in @source1 whose bit vectors intersected with those in @source2;
my ($intrx1_2, $intrx2_1) = set_intersection(\@source1,\@source2);


# Storing the results in a globally shared hash
$globally_shared_hash{$source1}->{$target2} = $intrx1_2;
$globally_shared_hash{$source2}->{$target1} = $intrx2_1;