note BrowserUk <blockquote><i></i></blockquote> <p>Try this. I project that it should complete your 410 billion comparisons in a little under 10 hours. <P>The main attempt at efficiency here is to invoke the regex once in global mode (/g) for each word, against a single large string containing all the words and have it return all the matches. It then filters just the matching ones for your specific exclusions. <code> #! perl -slw use strict; my @words = do{ local @ARGV = 'words.txt'; <> }; chomp @words; my $all = join ' ', @words; my $start = time; my $n = 0; for my $i ( @words ) { for my $j ( $all =~ m[ ([^ ]*$i[^ ]*) ]g ) { next if $j eq $i or $j eq "${i}s" or $j eq "${i}'s"; # print "$j contains $i"; } } printf STDERR "Took %d seconds for %d words\n", time() - $start, scalar @words; </code> <div class="pmsig"><div class="pmsig-171588"> <hr /> <font size=1 > <div>Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.</div> <div>"Science is about questioning the status quo. Questioning authority". </div> <div>In the absence of evidence, opinion is indistinguishable from prejudice.</div> </font> </div></div> 928877 928877