# Thread: The World's Hardest Logic Puzzle

1. I had taken a break from writing C-code when I looked at it, so I was still in the mind set of "short-circuit" logic, where A&&B would not evaluate B if A is false, but would if A is true, and I was assuming B would go into "infinite recursion."

But you are right, in standard logic, which is more appropriate, the use of the conjunction would a allow a decidable answer.

I like you solution a lot better, the assumption of Gods not being able to predict the answer for Random seems very reasonable to me. It would be interesting to find out if that's true.

In fact, it is so simple and clear, I think it is worthy of commendation even if not correct.

Edit: Point of clarification: I think Color's solution is correct. Just waiting on Merkw.

2. This reminds me of another puzzle, so I will just say... how's this for superiority over the divine: Ask all three gods whether the reply to the question will involve the word that means no. That will shut Truth up. ;)

3. Another, failed go at it, to add some food for thought.

Ask "Did A lie?" to B.
If A is True, and B is Random, you could get one of two combinations (no, yes) (no, no).
If B is false, you will get (no, no)
If A is random and B is true, you will get (yes, no), or (no, yes)
If A is random and B is false, you will get either (no, yes), or (yes, no)
If A is False and B is Random, you will get either (Yes, Yes), or (Yes, No)
If A is False and B is true, you will get (Yes, no)

If you get two different answers, you will know that the last god is either true or False, and you can ask "Are you true", to which both gods will answer the word that means "yes". this allows you to work out the other two answers, and would allow you to work out False, True, Random. (unfortunately, when looking at it this morning, it won't allow you to work out the other two combinations, and I don't think it will work out the combinations, since you can't figure out a way to avoid random for this question.)

I was hoping that if the first two questions got the same answer, i could arranged the third question so that if, say, all answers were the same it would mean that that answer meant "yes' or "no', but the random god screwed that up.

4. Originally Posted by Merkw
So far, I believe that Kiddo has gotten the farthest. In fact, I am not sure if realized or not, but I am quite sure that Kiddo is near the solution.
I give up. I've thought about at least a hundred different combinations of answers. I just want to take out a big sword and cut the bitch like good ol' Alexander.

5. each question must be put to exactly one god
Originally Posted by Colors
Question 3: Ask B 1st question: Does "ja" mean "yes"?
Wouldn't this be putting one of the questions to two gods? (Or are they considered two questions, even if they're identical? I guess it could be worked around by slightly changing it or asking does "da" mean "yes" instead by the way (flipping the expected answers)).

6. If the gods can only answer in truth or falsehood including Random does that mean that no one can answer in a parodox?

For example if I asked: Will your answer to this question be a lie? To answer "no" would be the truth, to answer "yes" would be a parodox, therefore by value of the fact that they have been asked this question they could not be False.

Or am I just making it too complex?

7. Originally Posted by Merkw
I stumbled across a riddle, titled by logician/philosopher George Boolos and conceived by Raymond Smullyan (mathematician/philosopher/logician/professional magician/pianist), which is, allegedly, one of the (if not the # 1) hardest logic puzzles to have existed. If you have heard of it, do not spoil the answer. Try to solve it on your own. Please do refrain from using external sources to find the answer.

Here it is:

Go for it.
"God A, are you the one who speaks the truth?"
"God B, Is God A the one who speaks the truth?"
"God C, Is God A the one who speaks the truth?"

The answers will tell me everything I need to know.

8. Originally Posted by Makaub
"God A, are you the one who speaks the truth?"
"God B, Is God A the one who speaks the truth?"
"God C, Is God A the one who speaks the truth?"

The answers will tell me everything I need to know.
Let's pretend you got the following answers:

A: da
B: da
C: ja

That could mean:
da means yes
God A is the one who speaks truth and answers truthfully.
God B is the random one and answers truthfully.
God C is the liar and lies.

Or it could also mean:
da means no
God A is random, and answers true.
God B is always true and answers true.
God C is lying and answers false.

There are several other possibilities, but these two alone reveal that you don't know everything you need from these three questions. (Unless the truthspeaker looks angelic, the liar looks demonic and the random god wears a question mark.)

9. Originally Posted by Makaub
"God A, are you the one who speaks the truth?"
"God B, Is God A the one who speaks the truth?"
"God C, Is God A the one who speaks the truth?"

The answers will tell me everything I need to know.
No they won't.

Say A is true, B is false, C is random.

A will answer whichever word means "yes".

B will answer whichever word means "no"

C will answer either "Yes' or "no".

If C answers no, you will get eithe 'ja, ja, na" or "na, na, ja", which would also be the answer order you get if A was false (yes), B was random and answered yes, and C was true (no)

If C answers yes, you get either (Na, Ja, Na) or (ja, na, ja), which would also be the order if A was random and answered yes, B was true and answered no, and C was false and answered yes. (there are other counterexamples, but this one gets the point across.)

10. Originally Posted by Mort Belfry
If the gods can only answer in truth or falsehood including Random does that mean that no one can answer in a parodox?

For example if I asked: Will your answer to this question be a lie? To answer "no" would be the truth, to answer "yes" would be a parodox, therefore by value of the fact that they have been asked this question they could not be False.

Or am I just making it too complex?
I like this approach. Then you will both know the meanings of "ja" or "da" and flush out False. Or could False just answer "no"? I'm so confused.

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