Knaves and Knights and Dancing Goblin Kings

Today, I share some Magic Dance, courtesy of Labyrinth and David Bowie, while I puzzle you with riddles.

Knights and Knaves is a logic puzzle created by Raymond Smullyan. It is based on the idea that you are a visitor on a fantastic island inhabited entirely by two groups of people – knights who never lie, and knaves who never tell the truth, and your job is to figure out who is who. 

Riddles like these are something I loved growing up. I got 2 of the following 3 questions right, I thought it would be fun to see how my readers fared..

Up for the challenge? 

Here is the scenario:

John and Bill are residents of the island of knights and knaves.

Question 1

John says: We are both knaves. 

Who is what?

Question 2

John: If Bill is a knave then I am a knave.

Bill: We are of different kinds.

Who is who?

Question 3

John and Bill are standing at a fork in the road. You know that one of them is a knight and the other a knave, but you don’t know which. You also know that one road leads to Death, and the other leads to Freedom. By asking one yes/no question, can you determine the road to Freedom?

**

Readers who have watched the film Labyrinth have a distinct advantage with that last question. 

I answered the first 2 very quickly, and while my logic seemed ok with the 3rd question, it wasn’t the right answer. 

Be brave, and comment your answers!

**

Are the puzzles still puzzling? Get your solutions here?

Advertisements
Published in: on December 9, 2008 at 2:50 am  Comments (2)  
Tags: , , ,

The URI to TrackBack this entry is: https://rivene.wordpress.com/2008/12/09/knaves-and-knights-and-dancing-goblin-kings/trackback/

RSS feed for comments on this post.

2 CommentsLeave a comment

  1. if you like puzzles of Raymond Smullyan, sure that this site (http://4chests.blogspot.com) will also enjoy it.

  2. Hey, bro! Good post, and merry Christmas; I hope you had a great day!

    I’d say the answer to your question posed at the end of puzzle number three is “yes.” You’d end up asking a question to one about what the other would answer. :o) “What would the other guy tell me is the road to safety?” (This way you’re guaranteed to incorporate the lie from whichever of them is the knave and thus you can pick the opposite path to the one you’re told. You’ll either be hearing a response from someone who is lying about the truth or someone who is telling the truth about a lie.)

    1. Four possibilities: 2 knaves; John is the only knave; John is the only knight; 2 knights. The only way that John could give this answer is if John is a knave and Bill is a knight. Try the others if you don’t believe me; it doesn’t work.

    2. Again four possibilities. They contradict each other by their statements, so this rules out the two cases where they are the same thing. Bill states this clearly, so he must be a knight and this leaves John to be the knave.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: