Saturday, July 26, 2008

xkcd conundrum

This post was originally written on 7 October 2008, shortly after the related xkcd cartoon was published.

I only discovered XKCD relatively recently (within the last couple of years, '06/'07) and it's not always as funny as it can be, but this particular cartoon got me thinking what I would do:
And over there, we have the labyrinth guards. One always lies, one always tells the truth, and one stabs people who asks tricky questions.
This is clearly a take on the old classic problem where you have to try and find out who's telling the truth, but with the added problem of not being able to ask tricky q's until you've figured out who the stabber is. Obviously you don't want to get stabbed. So perhaps the first question to ask would be "Are you going to stab me?" or similar to one of them. I'm assuming that's not tricky enough to elicit his stab response; but that anything with more than one clause in the question would see you lying in a pool of your own blood if you happened to ask a complex question.

If he says yes and doesn't stab you, he's the liar (but could also be the stabber ); if he says no he can't be the liar because he'd have to stab you and then he wouldn't be the liar - assuming mutual exclusivity of the 3 behaviour traits. Problem is, the way to identify more quickly who's who is to force him to try and stab you by asking a tricky Q which will figure out whether he's the liar or not, and hope you haven't picked the stabber; then run v.quickly out of stab-range after asking (but still so you can hear them)?. Mmm..


  1. But if you're allowed to do "out-of-puzzle" things like running away from the stabber, you might as well grab their spears and bash them over the head and get out that way.

  2. I would appreciate more visual materials, to make your blog more attractive, but your writing style really compensates it. But there is always place for improvement

  3. Do you have copy writer for so good articles? If so please give me contacts, because this really rocks! :)