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?

Since the native is "standing" at the fork I would need to ask just one question -
"Do you know they are giving free beer away in ____ (insert home villlage/town name)?

Knight or Knave (Truth first) would answer "NO" and head for the village. Follow him/her.
Liar or Knave (Liar first) would answer "YES" and head for the village. Follow him/her.

Problem solved.

Posted by Vernon Lewis on 2006-05-22 17:09:17