Take Two

Yesterday a friend mentioned that the word “bookkeeping” was (apparently) the only English word that had three consecutive groups of double letters in it. I decided to test this statement, so I wrote a little Perl oneliner. Here’s the program, and the results of running it:

narya:~% perl -n -e ‘print $_ if /(.)(?:\1)(.)(?:\2)(.)(?:\3)/’ /usr/share/dict/words
bookkeep
bookkeeper
bookkeeper’s
bookkeepers
bookkeeping
bookkeeping’s

So, it turned out he was (mostly) right. Then I got curious; what if the groups don’t have to be consecutive? That’s easy enough to check, so let’s do that:

narya:~% perl -n -e ‘print $_ if /(.)(?:\1).(.)(?:\2).(.)(?:\3)/’ /usr/share/dict/words | wc -l
118

Wow. I wonder if any of those have four groups of double letters in them?

narya:~% perl -n -e ‘print $_ if /(.)(?:\1).(.)(?:\2).(.)(?:\3).*(.)(?:\4)/’ /usr/share/dict/words | wc -l
0

Sadly, that’s a no.