use strict;
use warnings;
use Data::Dump qw/pp dd/;
use feature 'say';

my %hash = (
            'rendition' => '3',
            'automation' => '2',
            'saturation' => '3',
            'mass creation' => 2,
            'automation technology' => 2,
            'automation technology process' => 3
           );


# prepare sub-slices
my @slices;

my $max_del = 3;

for my $del ( 0 .. $max_del ) {
    for my $i (0 .. $del) {
        for my $l ( $i .. $del) {
            push @{ $slices[$del] }, [$i .. $l]
              unless $i==0 and $l == $del; # exclude identity
        }
    }
}

sub partitions {
    my $group =shift;
    my @words = split / /,$group;
    return map { join " ", @words[@$_] } @{$slices[$#words]}
}

delete @hash{ partitions($_) } for keys %hash ;

say "Result: ", pp \%hash;

say "# --- tests";

say '@slices = ', pp \@slices;

say "partitions('automation technology process limit') = " ,
  pp partitions('automation technology process limit');