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 Post subject: The Three Gods Riddle
PostPosted: Thu Feb 23, 2017 9:35 pm 
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The Three Gods

Three Gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter.

Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one God. The Gods understand English, but will answer all questions in their own language, in which the words for yes and no are “da” and “ja”, in some order. You do not know which word means which.

It could be that some God gets asked more than one question (and hence that some God is not asked any question at all).
What the second question is, and to which God it is put, may depend on the answer to the first question. (And of course similarly for the third question.)
Whether Random speaks truly or not should be thought of as depending on the flip of a coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.
Random will answer “da” or “ja” when asked any yes-no question.
What would your three questions be?

Answer:

Q1: Ask god B, “If I asked you ‘Is A Random?’, would you say ja?”.
If B answers ja, either B is Random (and is answering randomly), or B is not Random and the answer indicates that A is indeed Random. Either way, C is not Random. If B answers da, either B is Random (and is answering randomly), or B is not Random and the answer indicates that A is not Random. Either way, you know the identity of a god who is not Random.

Q2: Go to the god who was identified as not being Random by the previous question (either A or C), and ask him: “If I asked you ‘Are you False?’, would you say ja?”.
Since he is not Random, an answer of da indicates that he is True and an answer of ja indicates that he is False.

Q3: Ask the same god the question: “If I asked you ‘Is B Random?’, would you say ja?”.
If the answer is ja, B is Random; if the answer is da, the god you have not yet spoken to is Random. The remaining god can be identified by elimination.


Does the answer make any sense to you? I'm totally lost. For example, how does the answer to the first question eliminate C from being Random when da and ja are not defined?

Would you ask different questions instead?

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PostPosted: Fri Feb 24, 2017 1:42 am 
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Here you go, I made this diagram to explain part 1:
Image
http://imgur.com/oU59q2C.png

It's a case of compound binary logic, the Random mixes it up a bit, and the definition of the Random character's behaviour can alter the solutions a little, (ie, random can mean "it gives a random answer" or "it randomly decides whether or tell the truth" or "it's identity is randomly a truth teller or a liar for the duration of the puzzle" - but I think the solution you describe satisfies all cases.

The Random character is the big problem in this puzzle as you can't control their output. When you have a character who you know will always lie or always tell the truth you can control their behaviour even if you don't know which method they do. So the trick of the first question you ask is to be able to either identify random, or eliminate them. Because you may pick random, the only thing you can do is to identify a god who definitely isn't random.

If you pick Random, then it is certain that one of the others definitely isn't Random, however if you don't have Random, you need to ask a question that will allow you to know with certainty which of the other two isn't Random.

ie: if B *is* random it is a certainty that both A&C are not Random, so it doesn't matter that B answers randomly.

however: if B *isn't* random you need to have your answer enable you to identify who is Random, and then choose the other.

The Ja and Da is an extra layer of confusion, but it's basically building on basic logic principles of:

truth * truth = truth
false * truth = false
truth * false = false
false * false = truth

If you build tables like I did for the subsequent questions, you'll see how the puzzle works, but it's the first question that is the most important.


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PostPosted: Fri Feb 24, 2017 7:03 am 
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This makes me feel like my brain is made of mash potatoe.


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PostPosted: Fri Feb 24, 2017 8:32 am 
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:thumbup: for Alienturnedhuman.

I spent a while with a pen and paper and got some of it roughly worked out but I have to applaud your full in-depth explanation.


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PostPosted: Fri Feb 24, 2017 11:35 am 
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I do like a good brain frazzle in the morning :)

Just wish you hadn't put the answer in the OP. Reminds me of the riddle in The Labyrinth with the 2 doors, 2 creatures, 1 tells the truth and 1 lies and only 1 yes/no question to find out which door to gp through.

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PostPosted: Fri Feb 24, 2017 11:37 am 
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minchy wrote:
I do like a good brain frazzle in the morning :)

Just wish you hadn't put the answer in the OP. Reminds me of the riddle in The Labyrinth with the 2 doors, 2 creatures, 1 tells the truth and 1 lies and only 1 yes/no question to find out which door to gp through.


If you were the other one would you tell me to go in there?


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PostPosted: Fri Feb 24, 2017 12:18 pm 
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moby wrote:
minchy wrote:
I do like a good brain frazzle in the morning :)

Just wish you hadn't put the answer in the OP. Reminds me of the riddle in The Labyrinth with the 2 doors, 2 creatures, 1 tells the truth and 1 lies and only 1 yes/no question to find out which door to gp through.


If you were the other one would you tell me to go in there?

Depends which door you're asking about.

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PostPosted: Fri Feb 24, 2017 3:40 pm 
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minchy wrote:
moby wrote:
minchy wrote:
I do like a good brain frazzle in the morning :)

Just wish you hadn't put the answer in the OP. Reminds me of the riddle in The Labyrinth with the 2 doors, 2 creatures, 1 tells the truth and 1 lies and only 1 yes/no question to find out which door to gp through.


If you were the other one would you tell me to go in there?

Depends which door you're asking about.


Either one, then go in the other if its yes


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PostPosted: Fri Feb 24, 2017 9:27 pm 
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Location: Los Angeles, California
minchy wrote:
I do like a good brain frazzle in the morning :)

Just wish you hadn't put the answer in the OP. Reminds me of the riddle in The Labyrinth with the 2 doors, 2 creatures, 1 tells the truth and 1 lies and only 1 yes/no question to find out which door to gp through.


I don't post as often as I used to, so I forgot how to hide it. :lol:





Alienturnedhuman wrote:
Here you go, I made this diagram to explain part 1:
Image
http://imgur.com/oU59q2C.png

It's a case of compound binary logic, the Random mixes it up a bit, and the definition of the Random character's behaviour can alter the solutions a little, (ie, random can mean "it gives a random answer" or "it randomly decides whether or tell the truth" or "it's identity is randomly a truth teller or a liar for the duration of the puzzle" - but I think the solution you describe satisfies all cases.

The Random character is the big problem in this puzzle as you can't control their output. When you have a character who you know will always lie or always tell the truth you can control their behaviour even if you don't know which method they do. So the trick of the first question you ask is to be able to either identify random, or eliminate them. Because you may pick random, the only thing you can do is to identify a god who definitely isn't random.

If you pick Random, then it is certain that one of the others definitely isn't Random, however if you don't have Random, you need to ask a question that will allow you to know with certainty which of the other two isn't Random.

ie: if B *is* random it is a certainty that both A&C are not Random, so it doesn't matter that B answers randomly.

however: if B *isn't* random you need to have your answer enable you to identify who is Random, and then choose the other.

The Ja and Da is an extra layer of confusion, but it's basically building on basic logic principles of:

truth * truth = truth
false * truth = false
truth * false = false
false * false = truth

If you build tables like I did for the subsequent questions, you'll see how the puzzle works, but it's the first question that is the most important.


That's brilliant. :thumbup:

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"No, there is no terrible way to win. There is only winning."
Jean-Pierre Sarti


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PostPosted: Wed Apr 19, 2017 8:38 pm 
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Location: Fourth rock from the Sun!
Alienturnedhuman wrote:
Here you go, I made this diagram to explain part 1:
Image
http://imgur.com/oU59q2C.png

It's a case of compound binary logic, the Random mixes it up a bit, and the definition of the Random character's behaviour can alter the solutions a little, (ie, random can mean "it gives a random answer" or "it randomly decides whether or tell the truth" or "it's identity is randomly a truth teller or a liar for the duration of the puzzle" - but I think the solution you describe satisfies all cases.

The Random character is the big problem in this puzzle as you can't control their output. When you have a character who you know will always lie or always tell the truth you can control their behaviour even if you don't know which method they do. So the trick of the first question you ask is to be able to either identify random, or eliminate them. Because you may pick random, the only thing you can do is to identify a god who definitely isn't random.

If you pick Random, then it is certain that one of the others definitely isn't Random, however if you don't have Random, you need to ask a question that will allow you to know with certainty which of the other two isn't Random.

ie: if B *is* random it is a certainty that both A&C are not Random, so it doesn't matter that B answers randomly.

however: if B *isn't* random you need to have your answer enable you to identify who is Random, and then choose the other.

The Ja and Da is an extra layer of confusion, but it's basically building on basic logic principles of:

truth * truth = truth
false * truth = false
truth * false = false
false * false = truth

If you build tables like I did for the subsequent questions, you'll see how the puzzle works, but it's the first question that is the most important.


Hey, Alien, you were one of them kids who always put his hand up in maths cos you knew the answer, weren't you??

But then you do come from another world, so maybe you're Klaatu, just here on earth to test us inferior humans?

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PostPosted: Thu Apr 20, 2017 5:32 pm 
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Joined: Wed Aug 25, 2004 5:19 pm
Posts: 1129
Location: Los Angeles, California
moose22 wrote:
Alienturnedhuman wrote:
Here you go, I made this diagram to explain part 1:
Image
http://imgur.com/oU59q2C.png

It's a case of compound binary logic, the Random mixes it up a bit, and the definition of the Random character's behaviour can alter the solutions a little, (ie, random can mean "it gives a random answer" or "it randomly decides whether or tell the truth" or "it's identity is randomly a truth teller or a liar for the duration of the puzzle" - but I think the solution you describe satisfies all cases.

The Random character is the big problem in this puzzle as you can't control their output. When you have a character who you know will always lie or always tell the truth you can control their behaviour even if you don't know which method they do. So the trick of the first question you ask is to be able to either identify random, or eliminate them. Because you may pick random, the only thing you can do is to identify a god who definitely isn't random.

If you pick Random, then it is certain that one of the others definitely isn't Random, however if you don't have Random, you need to ask a question that will allow you to know with certainty which of the other two isn't Random.

ie: if B *is* random it is a certainty that both A&C are not Random, so it doesn't matter that B answers randomly.

however: if B *isn't* random you need to have your answer enable you to identify who is Random, and then choose the other.

The Ja and Da is an extra layer of confusion, but it's basically building on basic logic principles of:

truth * truth = truth
false * truth = false
truth * false = false
false * false = truth

If you build tables like I did for the subsequent questions, you'll see how the puzzle works, but it's the first question that is the most important.


Hey, Alien, you were one of them kids who always put his hand up in maths cos you knew the answer, weren't you??

But then you do come from another world, so maybe you're Klaatu, just here on earth to test us inferior humans?


I want his brain. :twisted:

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"No, there is no terrible way to win. There is only winning."
Jean-Pierre Sarti


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PostPosted: Thu Apr 27, 2017 12:33 am 
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Posts: 5248
Alienturnedhuman, you WERE on a TV show about speed dating weren't you!?


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