246: Labyrinth Puzzle

Explain xkcd: It's 'cause you're dumb.
(Difference between revisions)
Jump to: navigation, search
(Explanation: I believe that part was unnecessary. Consult me on my talk page if you believe otherwise.)
Line 8: Line 8:
  
 
==Explanation==
 
==Explanation==
This comic alludes to a famous {{w|Knights and Knaves}}-type logic puzzle, in which there are ''two'' doors and ''two'' guards. One guard always lies, and the other always tells the truth. One of the doors leads to freedom, and you can only ask one guard one question. The solution to this riddle involves a very tricky question indeed, and one would in the xkcd-version risk a stabbing from the third guard. If you want to give the original puzzle a try for yourself, don't read the spoiler in the next paragraph.
+
This comic alludes to a famous {{w|Knights and Knaves}}-type logic puzzle, in which there are ''two'' doors and ''two'' guards. One guard always lies, and the other always tells the truth. One of the doors leads to freedom, and you can only ask one guard one question. The solution to this riddle involves a very tricky question indeed, and one would in the xkcd-version risk a stabbing from the third guard.
 
+
Solution: Ask one guard (it doesn't matter which one) which door the other guard would say leads out. The door indicated does not lead out.
+
  
 
==Transcript==
 
==Transcript==

Revision as of 22:01, 7 October 2013

Labyrinth Puzzle
And the whole setup is just a trap to capture escaping logicians. None of the doors actually lead out.
Title text: And the whole setup is just a trap to capture escaping logicians. None of the doors actually lead out.

Explanation

This comic alludes to a famous Knights and Knaves-type logic puzzle, in which there are two doors and two guards. One guard always lies, and the other always tells the truth. One of the doors leads to freedom, and you can only ask one guard one question. The solution to this riddle involves a very tricky question indeed, and one would in the xkcd-version risk a stabbing from the third guard.

Transcript

Black Hat: And here we have the labyrinth guards. One always lies, one always tells the truth, and one stabs people who ask tricky questions.
comment.png add a comment! ⋅ Icons-mini-action refresh blue.gif refresh comments!

Discussion

Just ask which color is the sky.. ‎175.110.37.200 (talk) (please sign your comments with ~~~~)

Oh, although the strip doesn't explicitly say so; in those riddles you can normally only ask one question. --St.nerol (talk) 23:00, 27 January 2013 (UTC)
There's another (more traditional) three-guard variation where one guard always tells the truth, one guard always tells a lie and the third alternates between pure truth and pure lie (and you don't know which flip they're currently flopped upon). But you still only get to ask one question of one guard. Have fun with that one. My personal solution certainly has a degree of convolution, but I've heard other workable answers. 178.98.31.27 02:24, 21 June 2013 (UTC)
@‎175.110.37.200, you would know which one lies but you would not know which door leads out. Tharkon (talk) 23:13, 10 October 2013 (UTC)
Eh, well, even if you had a perfect question to ask in this case, a lot of good would that do you: it'd only reveal the truth behind the setup, that none of the doors lead out. :p -- 173.245.51.210 08:20, 8 November 2013 (UTC)
Well yes it says that in the title-text. But good pick-up. 108.162.219.58 02:31, 6 February 2014 (UTC)

One question, of one guard. I really like the original form of this riddle. It's a bit of a trick, though. It is crucial that the guards "know" each other's rules, but this is not even implied. And if it was stated in the question, that would probably be a good enough clue to get you to the answer. Of course, once you know the answer it seems trivial, but I wonder what percentage of people actually worked it out for themselves? Another good one is Monty Hall, even though that is pure, straightforward probability. 108.162.219.223 18:11, 17 January 2014 (UTC)

I think somebody needs a hug! 108.162.219.223 18:11, 17 January 2014 (UTC)
The whole problem with this entire riddle is that if they are both liars you are screwed! Nothing in the riddle establishes a fact that they aren't liars. Now if there was a known truth teller in the riddle that explains the nature of the guards or the narrator does it, then the above solution works. 108.162.216.28 (talk) (please sign your comments with ~~~~)
Personal tools
Namespaces

Variants
Actions
Navigation
Tools

It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal or Bitcoin?