You are lost once again in the land of Knights, Knaves, and Liars, and once again you find yourself at a fork in the road. You know that one path will lead you to a safe return home, while the other will lead you to your own gruesome demise. (You really need to find a better vacation spot next year!)

Standing at the fork is a native, who might be either a Knight (who always tells the truth), a Knave (who alternates between true and false statements), or a Liar (who always lies). You have no way of knowing which he is. Worse yet, you realize that if he is a knave, you don't know if he will tell you the truth first, and then lie, or lie first and then tell the truth, etc.

What is the fewest number of questions you have to ask to find out which is the safe road, and what are they?

(In reply to The jury isn't in. (re: question and solution) by Dej Mar)

Actually tats not true. I think Robby's qn is the correct one. You do not end with with that neverending paradox u talk about because the opposite has to giev a clear cut answer which the person either trasmites or negates depending on whether he is lying or not. Now suppose we have the case of the person being a Knight. So the opposite is a liar. Thus for the qn, the opposites answer is the correct route, which the knight just tells me and i cant take it. Now suppose it was the other way round. The opposite says teh wrong route which the liar negates for me so i am still ok. The same thing can be done with the 2 knaves and we r ok. So the answer is one qn!

Posted by Venkat on 2006-05-24 23:44:13