sub induced { my (@z)=@_; for my $QT (\@z ){ #print Dumper $QT; for my $triplet ( @trip ){ my %Pie; undef @Pie{@$QT}; delete @Pie{ @$triplet }; print "@$triplet\n" if keys(%Pie) <= ( @$QT - @$triplet ) ; return @$triplet; } }} my @C; my $d; my $p=$#subgraphs+1; for ($d=$p; $d >=1; $d--) { print "component $d = @{ $subgraphs[$d-1] }\n"; my ($qw,$we,$er)=&induced(@{ $subgraphs[$d-1] }); } ----------OUTPUT------------ component 2 = e d component 1 = c a b b c a