#....
    my @accum;
    foreach  my $int (@intervals )
    {
       if (num_of_tupl($int) >= 4)
       {
          print Dumper $int;   # It prints correctly in this line
          push @accum,$int;
       }
    }    
    print "ACCUM: ";
    print Dumper \@accum ;  # Problem here

##</code><code>##

$VAR1 = 
       [
        [['A','3','C']],
        [['C','-4','B'],['B','-4','A'],['A','3','C'],['C','-4','B']]
       ];
$VAR1 = 
       [
         [['A','3','C'],['C','-4','B'],['B','-4','A'],['A','3','C']],
         [['C','-4','B']]
       ];

# Problem begins here
ACCUM BOTH ABOVE:
$VAR1 = 
      [[
        [['A','3','C']],
        [['C','-4','B'],['B','-4','A'],['A','3','C'],['C','-4','B']]],

        [[$VAR1->[0][0][0],
          $VAR1->[0][1][0],
          $VAR1->[0][1][1],
          $VAR1->[0][1][2]],
         [$VAR1->[0][1][3]]]
       ];


##</code><code>##

#!/usr/bin/perl -lw
use strict;
use Algorithm::Loops 'NestedLoops';
use Data::Dumper;
$Data::Dumper::Indent = 0;

my $set = {
  'key1' => 
  ['A -4 A','A -1 C','C -4 D','D -4 B','B -3 C','C -4 B','B -1 E'],
  'key2' => ['A -1 B','B -1 C','C -4 A','A -5 B'],
  'key3' => ['A 3 C','C -4 B','B -4 A','A 3 C','C -4 B'],
};
my $delim    = 'A 3 C -4 B';


get_region_wth_idx($delim,$set);



sub get_region_wth_idx
{
    my ($delim,$set) = @_;
    my %hash;

    OUT:
    foreach  my $setkey ( sort keys %{$set}  )
    {
        print "\n";
        print "$setkey\n";

        my @delim = decomp_str2aoa($delim);
        my @data  = decomp_a2aoa($set->{$setkey});

        my $N = $#data;
        my $D = $#delim;

        my @intervals  =  
        NestedLoops(
                    [    [0    .. $N],  sub {[$_ .. $N]},
                      ( sub {[$_+1 .. $N]}, sub {[$_ .. $N]} ) x $D
                    ],

            { OnlyWhen => sub {
                    
                return 0 if @_ < 2*@delim;
                for my $d (0 .. $D) {
                  
                  if ($data[ $_[ $d*2     ] ][0] ne $delim[$d][0]
                  or  $data[ $_[ $d*2 + 1 ] ][2] ne $delim[$d][2])
                    {
                        return 0;
                    }
                }
                return 1;
            } },
            
            sub {
             return [ 
                     map { [@data[ $_[2*$_] .. $_[2*$_+1] ]] } 0 .. $D
                    ]; 
                
            }
         );
            my @accum;
            foreach  my $int (@intervals )
            {
                if (num_of_tupl($int) >= 4)
                {
                    print Dumper $int;
                    push @accum,$int;
                }
            }    

             print "ACCUM BOTH ABOVE: ";
             print Dumper \@accum ;
    }               
    
    # $hash{$setkey} = [ @accum ];
    # print Dumper \%hash ;  	
	print "\n";
    return ;
}	


#--------- Additional subroutine -------
sub num_of_tupl
{
    # Just a simple code, counting
    # how many tuples (e.g.["A", -3, "C"] ) contain in AoA
	my	$ar	= shift;
    my $count;
    
    foreach  my $lvl1 ( @{$ar}  )
    {
        my $sizein = scalar(@{$lvl1});
        $count += $sizein;
    }  
	return $count;
}	

sub decomp_str2aoa 
{
    return 
    decomp_a2aoa([$_[0] =~ /(?=([a-z]\s*(?:\S+\s*){2}))\S+\s*/gi]);
}

sub decomp_a2aoa
{
	my	$arr	= shift;
    return map{ [split(" ",$_)] }@{$arr};
}