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Masters of Logic Puzzles III. (stamps)


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32 replies to this topic

#21 ALFRED

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Posted 19 March 2008 - 06:42 PM

I understand the puzzle asks if B replies "Yes" during the second turn, what are her stamps and what is the situation, but why couldn't person A answer "Yes" during the second turn and state that she has the two opposite colors of person C?
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#22 tink

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Posted 20 March 2008 - 02:40 AM

B could have one of each by discareding situations
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#23 P Man

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Posted 20 April 2008 - 09:59 PM

how many logicists are there?
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#24 Following_my_dream

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Posted 21 April 2008 - 02:15 AM

I think that B only said yes so that they wouldn't have to keep playing this stupid game with stamps on their heads. loll. :)
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#25 Mohar

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Posted 25 April 2008 - 10:44 PM

This is a useless praise post:

Good puzzle! Took me a bit.


And, if there is any further doubt, I agree that it was completely unambiguous- just tricky.
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#26 octopuppy

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Posted 15 May 2008 - 04:18 PM

Nice puzzle, though I don't think you needed to reveal B's second answer. The first four responses:
A: "No."
B: "No."
C: "No."
A: "No."
left only one possible answer for B
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#27 octopuppy

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Posted 15 May 2008 - 04:57 PM

Here's a quick variation. They played again, same rules except this time everybody answers twice even if somebody has already said "Yes".

A: "No"
B: "No"
C: "No"
A: [ history has not recorded what A's second answer was ]
B: [ nor B's ]
C: "Yes"

What were A and B's second answers?
Spoiler for Answer

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#28 fisk88

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Posted 14 June 2008 - 09:39 PM

i think this does'n make any sense because they don't know the colour of the 2 stamps in the moderators poket "each logician can see all the other stamps except those 2 in the moderator's pocket and the two on her own head"
or if they all have red and green on their head this doesn't work either
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#29 DugALug

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Posted 19 June 2008 - 04:52 PM

Though I have heard this one before, I think that your question gives away the answer, unless the answer was "the color can't be determined, but they are the same color".

The stamps have to be one of each color by the phrasing of the question, else they color could not be isolated.

Still a good riddle.

-Doug

Edited by DugALug, 19 June 2008 - 04:53 PM.

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#30 flewk

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Posted 24 July 2008 - 11:37 AM

Arbitrarily, I chose x:y, x=red, y=green. 3-1 for AC would mean RRRG or GRRR.
A 1: says no so everyone knows BC isn't 4-0 0-4 so only possibilities for BC are 3-1 2-2 1-3 1-1-1-1. (RGGG GGGR GGRR RRGG RRRG GRRR GRGR)

B 1: B also says no which means everyone knows AC isn't 4-0 0-4. B sees 3-1 2-2 1-3 1-1-1-1 possibilities for AC.

C 1: says no when she knows BC and AC both don't have 4-0 or 0-4. If she sees AB = 2-2 then she would know she has RG. For AB = RRGG GGRR C must be RG or else AC or BC would have been 4-0 0-4. Therefore C didn't see 2-2 because she said no. Since AB can't be 2-2 everyone knows possible AB are 1-3 3-1 1-1-1-1.

A 2: says no so BC can't be GGGR RRRG RRGG GGRR or else A would be RG because if A is RR/GG while BC is any of those then AB would be 2-2. A knows AB can't be 2-2 from C 1 saying no. All thats left for BC is RGGG GRRR GRGR.

B 2: figures it out from A 2 saying no. BC can only be GRRR or RGGG or GRGR and all three have B as RG.

Don't know if this is more clear.
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