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#51 bonanova

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Posted 24 January 2013 - 12:46 AM


 


I'm taking a slightly stricter view, that NEWS coding is not available.
Wolfgang has allowed that prisoners can either face toward or away from the door.
That is, NS (or EW, as I drew it) coding is available, and that requires two prisoners to signal a color.

That presents a particular problem for P2 on initial entry, but I think it can be worked around.

 

If only a binary signaling scheme is allowed, CaptainEd has shown that only prisoner 1 needs to change his mind. Even in the stricter NS view, there are some latitude to define a quadnary signaling scheme due to an implied necessary condition

Spoiler for because
  You're right.NS signaling is enough.Four easily distinguishable rotations: None, 180ocw, 180occw,  and 360occw.And entering prisoners must be able to see the rotation. I think we spent most of the time on this puzzle with a poor understanding of the conditions.But it was fun to finally solve something possible.It's just that the problem became teasing out the constraints that admitted a solution!Bertrand was helpful in this case. ^_^ Thanks, Wolfgang.
I want to thank you all....I was thinking like this:After the first three prisoners took their right places,they all should be facing the door, the possible combinations would be:Yellow,Green,Red,........Yellow,Green,........,BlueYellow,.........,Red, Blue.........,Green, Red, Blueso when the 4th one enters, Let him to have  X color..the X one standing in the raw will turn his face to the wall,and the new comer will stand in that raw facing the door....and when nobody turns to the wall so he should stand at the empty place facing the door.when the four raws are made, each new comer will  know where he belongs  when the man with the same color turns his face toward the wall.
The first three may not all be different.
What if all the prisoners are say red, except for the last three to make all the colors used?

Edit: ok, that's not a problem I guess, it just delays the row formation.
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
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#52 phaze

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Posted 24 January 2013 - 04:25 AM

Spoiler for


Edited by phaze, 24 January 2013 - 04:28 AM.

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Perfecting Mafia suicide since August 2008

#53 phaze

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Posted 24 January 2013 - 04:32 AM

Spoiler for Should even work


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Perfecting Mafia suicide since August 2008

#54 bonanova

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Posted 24 January 2013 - 08:59 AM

There are two constraints from a normal reading of the OP

that, when combined, render the puzzle impossible:

  1. No communication.
  2. Enter and take position singly.

We've now shown that if either is relaxed the puzzle has a solution.


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

#55 Prime

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Posted 24 January 2013 - 10:28 AM

There are two constraints from a normal reading of the OP

that, when combined, render the puzzle impossible:

  1. No communication.
  2. Enter and take position singly.

If we drop either, the puzzle has  a solution.

If we drop (1), it's not really a puzzle.

There are more than 14 men on the death row. Which means they are either prisoners of war, or this whole thing takes place in Texas. Either way most of them are innocent in all likelyhood. With such obvious signaling as turning around, they are all doomed. I would choose some more inconspicuous signal, like someone in the formation turning the toe of his left foot inside ever so slightly.


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Past prime, actually.


#56 TimeSpaceLightForce

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Posted 24 January 2013 - 04:36 PM

Spoiler for too much beer last night


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#57 CaptainEd

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Posted 24 January 2013 - 04:37 PM

Prime, I agree--dropping (2), as you and Rainman did, was more interesting. I was excited to see the Rainman solution, and I then admired your transformation so that people could tell where the colors are even without colored chairs.


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#58 TimeSpaceLightForce

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Posted 24 January 2013 - 04:59 PM

This is a challenge.
A two-color version requires and permits movement after taking one's position.
So I don't think it provides useful guidance for this case

Spoiler for here it is anyway

Great puzzle.
Eager to see the solution.

 

Spoiler for


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