Jump to content


Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.

Of course, you can also enjoy our collection of amazing optical illusions and cool math games.

If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.

Thanks and enjoy the Den :-)
Guest Message by DevFuse
 

Photo
- - - - -

A stand up Logician


  • Please log in to reply
7 replies to this topic

#1 BMAD

BMAD

    Senior Member

  • Members
  • PipPipPipPip
  • 1658 posts
  • Gender:Female

Posted 27 May 2013 - 12:42 AM

Recently a self-proclaimed stand-up logician held a show with thirty people.  here is his opening dialogue:
 
 
Hello folks. It's an honor to be on Amateur Logician Night, here on the Internet. How many of you are from out-of-town? Let's see a show of hands.
 
Now, the people who raised their hands may be truth-tellers who are from out-of-town, or you may be liars who are from in-town. As the amateur logician, it is my job to determine who is really from out-of-town, and who is not. This is not an easy job, as you can well imagine.
 
If I were to ask how many of you are truth-tellers, then all of you would raise your hands. The liars would have to lie, and claim to be truth-tellers.
 
Now, let's see a show of hands, all of the people who raised your hands the first time, when I asked how many of you were from out-of-town. Very good. All of you, who now have your hands up, are from out-of-town.
 
Some of you are truth-tellers who raised your hands both times. You are from out-of-town. Some of you are liars who did not raise your hands last time. You too are from out-of-town. So, all of you who now have your hands up, are from out-of-town.
 
Thank you. Thank you. What a crowd. Thank you.

 

 

Would this approach work in identifying those that always lie and those that always tell the truth?  Why or why not?


  • 0

#2 bonanova

bonanova

    bonanova

  • Moderator
  • PipPipPipPip
  • 5529 posts
  • Gender:Male
  • Location:New York

Posted 27 May 2013 - 03:53 PM

Spoiler for Slight change in the process does it


  • 0
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#3 bhramarraj

bhramarraj

    Advanced Member

  • Members
  • PipPipPip
  • 254 posts

Posted 28 May 2013 - 02:57 PM

Spoiler for


  • 0

#4 BMAD

BMAD

    Senior Member

  • Members
  • PipPipPipPip
  • 1658 posts
  • Gender:Female

Posted 28 May 2013 - 03:21 PM

[quote name="BMAD" post="332585" timestamp="1369611752"]

Now, let's see a show of hands, all of the people who raised your hands the first time, when I asked how many of you were from out-of-town. Very good. All of you, who now have your hands up, are from out-of-town.
 
Spoiler for curious

  • 0

#5 bonanova

bonanova

    bonanova

  • Moderator
  • PipPipPipPip
  • 5529 posts
  • Gender:Male
  • Location:New York

Posted 28 May 2013 - 06:29 PM

Spoiler for No

  • 0
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#6 kingofpain

kingofpain

    Advanced Member

  • Members
  • PipPipPip
  • 354 posts
  • Gender:Male

Posted 28 May 2013 - 07:19 PM

Depends on if a lie means the person evaluates the statement and then inverts his answer

(For an out of town liar:

You: Are you from out of town? 

OOTL: *I am indeed from out of town. So I will lie and say NO*

You: If you raised your hand last time, then raise it again.

OOTL: *I did not raise my hand last time, so this time I should do so*

)

 

However, a perfect liar would give you the answer that will prevent you from knowing the truth by withholding information. In this case, that would mean telling the truth when it is likely to lead you to misinterpret the truth or at least not know it.


  • 0

#7 bonanova

bonanova

    bonanova

  • Moderator
  • PipPipPipPip
  • 5529 posts
  • Gender:Male
  • Location:New York

Posted 30 May 2013 - 05:30 AM

Spoiler for Slight change in the process does it


Spoiler for Clarifying

  • 1
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#8 bhramarraj

bhramarraj

    Advanced Member

  • Members
  • PipPipPip
  • 254 posts

Posted 30 May 2013 - 08:03 AM

Sorry...! My last reply was posted in a hurry as I was called to attend an urgent meeting. There were mistakes in the post

Spoiler for how a liar would act
.


Edited by bhramarraj, 30 May 2013 - 08:06 AM.

  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users