The Blue-Eyed Islanders

This puzzle is variously attributed (including to “some dude on the street in Boston named Joel”), and was contributed by Manoj Gupta in our first meetup.

You can read up on a relatively standard version of the puzzle from Terrance Tao’s blog or here at XKCD.

Akash proposed a variation where not everyone sees everyone, but people see each other via a graph. What goes on in such a setting? We don’t quite know!

The links have pointers to other variants and the blog also sparked a rather long discussion — enjoy thinking about this and looking things up!