All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic > Liars and Knights
Odd people (Posted on 2005-09-12) Difficulty: 3 of 5
As everyone knows, knights tell the truth all the time, and liars lie all the time. At least, this is what evenly behaved knights and liars do.

Less known is that there are also odd knights, who on odd-numbered days lie all the time. (On even-numbered days, however, they behave evenly, and tell the truth.) Also, there are odd liars, who on odd-numbered days, tell the truth about everything, while they lie the rest of the days.

Someone said: "Today's the 3rd. Trust me, I'm telling the truth. I'm odd. I didn't lie yesterday. I'm not a knight."

At first, this seemed illogical, and I thought he couldn't be either a knight or a liar, even or odd, but after a while the solution dawned on me and I found the error in my reasoning. What is he?

  Submitted by e.g.    
Rating: 4.4444 (9 votes)
Solution: (Hide)
He cannot be normal (knight or liar) for he couldn't say he isn't a knight.

He cannot be odd (knight or liar) on an even day, for the same reason.

Thus, it must be an odd day. But an odd knight couldn't say he was odd... so he must be an odd liar, who had laryngitis yesterday and thus didn't speak at all!

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionOdd solutionMath Man2012-06-24 21:03:13
No SubjectTerence2005-10-06 17:33:44
Some Thoughtsre: Solution (Wrong)e.g.2005-09-28 18:42:29
SolutionGoldwing2005-09-17 00:32:40
SolutionSolutionLouise2005-09-13 05:24:30
Some ThoughtsWho's the real liar?Leming2005-09-12 19:05:08
re: Lisa's pointCharlie2005-09-12 17:43:48
A cop outOld Original Oskar!2005-09-12 16:42:49
Some ThoughtsLisa's pointFederico Kereki2005-09-12 15:51:27
Some Thoughtsre(2): a solution?Old Original Oskar!2005-09-12 15:35:53
SolutionAnalysisFederico Kereki2005-09-12 15:30:19
Some Thoughtsre: a solution?Lisa2005-09-12 15:28:48
Some Thoughtsa solution?Charlie2005-09-12 14:27:26
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (45)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (6)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2019 by Animus Pactum Consulting. All rights reserved. Privacy Information