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#41 CaptainEd

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Posted 21 January 2013 - 06:45 PM

Channeling other denizens, as we all thought this would constitute "communication", hence illegal.

Spoiler for Arrival of third prisoner ("C")


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#42 bushindo

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Posted 21 January 2013 - 07:10 PM

your method is successful with the first two prisoners, but you should find a very simple,uncomplicated way for the 3rd one,if you find it, the rest will be very easy and straight forward job.

 
 

How about this *very easy and straight forward* method?

Spoiler for

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#43 CaptainEd

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Posted 21 January 2013 - 07:17 PM

Good point, Bushindo! Prisoner 2 is the first one who knows both colors, so he adopts a position that makes Prisoner 1's location correct as well. And, following TSLF's suggestion of NEWS-coding, Prisoner 1 tells all arrivals their own color.

 

Very pretty!


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#44 bonanova

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Posted 22 January 2013 - 02:28 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.


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

#45 TimeSpaceLightForce

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Posted 22 January 2013 - 02:48 AM

Spoiler for visibility


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#46 CaptainEd

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Posted 22 January 2013 - 03:39 PM

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.

So, my solution, spread out over 38, 39 and 41 solves this, right?

Spoiler for see 38 for details


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#47 bushindo

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Posted 22 January 2013 - 05:50 PM

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


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#48 bonanova

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Posted 22 January 2013 - 09:20 PM

 

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.


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

#49 wolfgang

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Posted 23 January 2013 - 06:49 PM

 

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,........,Blue

Yellow,.........,Red, Blue

.........,Green, Red, Blue

so 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.


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#50 Prime

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Posted 23 January 2013 - 07:02 PM

Turning around when new man enters is clearly a communication. And the OP said:

An unknown number of prisoners( more than 14)were told a day before their execution, that they are going to be blind folded, and a colored paper(either.. yellow,green,red or blue) will be  glued on forehead of each one of them( no one can see his own paper), then they should inter a big hall one by one to make 4 raws in this order( Yellow,Green,Red,Blue)i.e. a raw of Yallows, a raw of Greens  etc.,each one will be unfolded when he inters the hall.No one of them is allowed to arrenge the others,each one should himslf choose where to stay, once he did,he can not change his place( only the first 2 prisoners can change their minds only once).Any kind of comunication between them is not allowed. If any one of them stands in a wrong raw, all of them will die!

All colores were used.

They should make a plane which saves all of them, can you help them?

 


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Past prime, actually.





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