Hadn't got much to do, so I thought I'd give it a stab:

use strict;
use warnings;

use Math::Combinatorics;

# Probably best to get stopwords from a file, but for testing:
my @stopwords = qw/ the of in on with by and /;
my %stop_hash = map { $_ => 1 } @stopwords;

my $term = 'Programming Perl, by Wall, Christiansen and Orwant';
my @term = grep { not $stop_hash{lc $_} } split ' ', $term;

# Default highlighting combination: n-1 from n (3 from 4, 5 from 6..)
my $n_from = shift || @term - 1; 

my @combos = combine( $n_from, @term );

my $result = highlight( \@combos, $term );
print join "\n", @$result; 

sub highlight {
  my $to_highlight = shift;
  my $term = shift;

  my @highlighted;
  foreach my $combo ( @$to_highlight ) {
    my $str = $term;

    # Highlight with Caps for console output
    # $str =~ s/$_/<em>$_</em>/ for @$combo;
    $str =~ s/$_/\U$_/ for @$combo;

    push @highlighted, $str;
  }
  return \@highlighted;
}
[download]

Output

PROGRAMMING PERL, by WALL, CHRISTIANSEN and Orwant
PROGRAMMING PERL, by WALL, Christiansen and ORWANT
PROGRAMMING PERL, by Wall, CHRISTIANSEN and ORWANT
PROGRAMMING Perl, by WALL, CHRISTIANSEN and ORWANT
Programming PERL, by WALL, CHRISTIANSEN and ORWANT
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.