This is often called the hardest riddle ever created. An astronaut is stranded on a distant planet, and the only way to escape is to identify and give the correct artifacts to three alien gods, after asking three questions that can only be answered with "yes" or "no". But there are several problems: you don't know which god is which, one always tells the truth, another always lies, and the third answers randomly. Finally, you can't tell whether their words "ozo" and "ulu" mean "yes" and "no" or the reverse...
The Scenario
An astronaut crashes on an unknown planet after a ship malfunction. After studying some ruins, he manages to partially decipher the local language, and the inscriptions indicate that to escape, he must appease three gods, giving each the correct artifact. The names of these gods are Tee, Eff, and Arr.
The Rules
Now, the astronaut doesn't know who is who, but he is allowed to ask three questions, which will be answered with "yes" or "no". And the rules don't end there. Tee always tells the truth, Eff always lies, and Arr answers randomly. As if that weren't enough, the partial translation prevents you from determining whether the words "ozo" and "ulu" mean yes and no, or the reverse. In short: three questions to be answered with yes or no.
The gods will say ozo or ulu, and you don't know the difference between the two expressions. You can ask one question at a time per god, although you can ask questions to a single one in succession, and take all the time you need, meaning you can formulate the next question based on what you've learned from the previous one. Ready?
The Solution
Needless to say, the challenge is enormous. The critical obstacle is that you don't understand the answers to your questions, and at the same time you don't know if they are true or false. However, there is a way. It is extraordinarily complicated—after all, the video needs just over three minutes to explain it—but I will try to summarize: The important thing is not to establish what ozo or ulu mean, but to confirm the identity of each alien, which at the end of the day is what will get you off the planet. The first question is used to identify a god that is "not" Arr, the second to determine if it is Tee or Eff, and the third to identify one of the others.
So, the question to the center god is: "If I asked you if the god to my left is Arr, would you answer ozo?" If he indeed answers ozo, there are two options: either you are already talking to Arr, or the center god is Tee or Eff, eliminating the possibility that the god on the right is Arr. On the other hand, if he answers ulu, the one eliminated is the god on the left.
The second question is for the god that is "not" Arr, and it says: "If I asked you 'Are you Eff?', would you answer ozo?" As the random factor has been eliminated, whatever the answer, it confirms his identity.
Finally, we ask the third question to that same god: "If I asked you if the center god is Arr, would you answer ozo?" and by elimination, the remaining god is identified.
Personally, I want to make a confession: I didn't understand it. I admit it, I am Spartacus. I went over it half a dozen times, and the blue screen in my brain is still there...
