  This is the extended version of a Comment submitted to Physical Review
Letters. I first point out the inappropriateness of publishing a Letter
unrelated to physics. Next, I give experimental results showing that the
technique used in the Letter is 3 times worse and 17 times slower than a simple
baseline. And finally, I review the literature, showing that the ideas of the
Letter are not novel. I conclude by suggesting that Physical Review Letters
should not publish Letters unrelated to physics.
