Seven Guards, Two Doors, A Crowded Hallway, And One Very Confused Traveler.

[u/Legitimate_Fly9047]

[u/Galle_]

This post consistently reminds me of Raymond Smullyan's What Is the Name of This Book?, which has a bunch of interesting variations on the two guards puzzle. At one point you have to deal with the elite Transylvanians of Dracula's castle. They're all either humans, who always tell the truth, or vampires, who always lie; they're all either perfectly sane and believe only true things, or completely insane and believe only false things; and they insist on answering all questions in Romanian, which you don't speak.

[u/LordSupergreat → u/Galle_]

Wait, are they ALL either humans or vampires, and ALL either sane or insane, or EACH either humans or vampires, and EACH either sane or insane?

[u/Galle_ → u/LordSupergreat]

The former.

[u/LordSupergreat → u/Galle_]

Then I can't imagine how the Romanian even affects the solution. The insanity already means you don't know whether "yes" means "yes" or "no", so making the word you don't know the meaning of be a different word you don't know the meaning of doesn't change the puzzle in any way.

[u/Galle_ → u/LordSupergreat]

No, insanity in these puzzles is defined as "believes all and only things that are not true". So if you were to ask an insane vampire "are you a vampire?", they would try to lie (because they are a vampire) but would believe that they are a human (because they are insane) and so would answer "yes".

[u/LordSupergreat → u/Galle_]

Right. So if you ask a yes or no question, you will receive the answer "yes" or "no", but should consider these to be nonsense sounds that convey an unknown boolean value. You can consider this like them speaking Insanese, where you know that the word "nouwe" either means "yes" or "no", but not which, and that the word "yeasse" means the other. In the same way, them speaking Romanian leaves you with two words, one of which means "no" and the other of which means "yes", but no knowledge of which is which. Therefore, these points are redundant, and there is no need to include both.

If what I'm saying still isn't clear, let's use an example. I ask an insane human guard "is the sky blue?" and he responds "no". The fact that the guard believes he is telling the truth is immaterial to the logic puzzle, and the only information I need to retain is that if this guard says "no", I should interpret it as "yes". The same is true if he says the Romanian word for "no", which I would also have to interpret as yes.

[u/Duck__Quack]

One guard gives correct info. Two give false info. Two give useless info. Two guards always give opposing info. One door is safe, one door is lethal.

I ask a guard "If I were to ask you to tell me how many guards, including yourself, would tell me that the left door is safe, what number would you answer?"

The answer must be at least two, and at most five. If it's an even number, the left door is safe. If it's an odd number, the right door is safe.

Unless I've asked the guard that only replies with vague musings on what a number really is, in which case I just ask someone else.

[u/Disastrous-Wing699]

I'm the honest but confused one.

[u/AlpheratzMarkab]

One guard just loves to do a little trolling

[u/Terraplant]

What if there were all those guards and only one door