This is an edited, updated version of an essay I wrote in 2008 when this now popular idea was embryonic and ragged. I recently rewrote it to convey the core ideas, minus out-of-date details. This ...

As avid puzzlers know full well, the humble jigsaw puzzle is a thing of beauty in multiple ways. Not only are jigsaws an absorbing time sink, but multiple studies have demonstrated they are good for ...