my $abstract = 'Perl is a high-level, general-purpose, 
interpreted, dynamic programming language.';


my $maxphraselength = 4;
my $minphraselength = 2;
my %phrasearray;
my ($i,$offset);

$abstract =~ s/\n|\r//g;

for ($i=$minphraselength; $i<$maxphraselength; $i++) {
  for ($offset=0; $offset<$i; $offset++) {
  while ($abstract =~ /(\w+\W+){$offset}((\w+\W+){$i})/) {
    $phrasearray{$2}++;
  }
 }
}
foreach(keys %phrasearray){ print $_."\n"; } #sample output