Those of you who were around for the very first Weekly Warlock Wind-Up (before it was even called that) nearly a year ago will remember that it was actually nothing more than a puzzle about light bulbs which I had come across in passing. And this week’s puzzle is exactly the same!
So, observe the set-up below. I have four light bulbs arranged with a switch in between each pair, and one bulb is turned on. When I flip a switch, it changes the states of the two light bulbs it is between i.e. if both adjacent bulbs are on, they will both turn off, and so on. My question is thus: is it possible to keep flipping switches so that all four bulbs are lit? If so, how, and if not, why not?
All will be illuminated on Friday…