Can you solve the three gods riddle? - Alex Gendler

TEDTED-EdTED EdTED EducationAlex GendlerArtrake Studioriddleproblem solvingcritical thinkingRaymond SmullyanGeorge Boolos

View full lesson: http://ed.ted.com/lessons/can-you-solve-the-three-gods-riddle-alex-gendler

You and your team have crash-landed on an ancient planet. Can you appease the three alien overlords who rule it and get your team safely home? Created by logician Raymond Smullyan, and popularized by his colleague George Boolos, this riddle has been called the hardest logic puzzle ever. Alex Gendler shows how to solve it.

Lesson by Alex Gendler, animation by Artrake Studio.

Laura Clark
My answer (definitely not the one provided):
Q1: Would Arr say [ozo/ulu] to "does 2+2=4?" Only Arr knows, Tee and Eff will respond "I don't know" or "I definitely know" in order to accurately be truthful/lie respectively, while Arr would answer "ozo" or "ulu". With this question, you have determined the identity of one overlord.
Q2: Same thing, but to a different overlord. Now just use process of elimination, and done!
yugijak
Hmm...I think this is like the riddle with the two guards. One who lies and one who tells the truth. The added challenge being you have an inconsistency you have to find a way to overcome. Interesting.

The biggest issue is that one answers randomly. You cannot be sure which one is the random answering one. So...
I think there needs to be 1 question that you can outright tell the correct answer two. It doesn't have to be 2+2=4 but it has to be something immediately able to have a correct and incorrect answer of true and false respectively.

The trick is largely eliminating 1 alien outright. You cannot ask them all 1 question at the same time which would help expose the randomly answering one.

Here's my thought: Take 1 alien. Ask them the following question twice: Are there three alien overlords? The Random answering alien...Arr...cannot answer the same way twice. If he did his answer would not be random, but consistent. Arr has to change his answer every time for it to be a random answer. Thus, if the alien answers the same way twice, it is not Arr but Tee or Eff. If he does not answer the same way twice, then it is Arr. Then take either of the other two aliens and ask them the same question. Eff will answer false, and Tee with answer true, leaving the leftover alien as whoever did not speak.

I'm probably wrong but...that's my theory. Time to see if I was right.
ninjakiwirules
You asked four questions. The math question to figure out ozo/ulu is still a question
Ethan Butler
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JJ_12
I believe I have found an alternate solution that allows you to know which alien word (Uzu or Olo) is yes and which is no. If we have 3 aliens, then there are six different positions in which Arr(r for random), Tee(t for true), and Eff(f for false) could be standing: 1.r,t,f 2.r,f,t 3.t,r,f 4.t,f,r 5.f,r,t 6.f,t,r

Regardless of the alien's order, we have 3 objectives:
1. determine which alien is r.
2. Determine which word is the negative.
3. Determine who is who between t and f.

The key question we are going to use (and slightly vary depending on responses) is "Would the alien in the position next to you say 2+2=4?" There are 3 different responses to this. R would say either positive or negative, since he is random. If you ask the question to t or f and their counterpart is in the next position, both of them will answer negatively, since t will be truthful and say f would not say 2+2=4, and f would lie and say t would not say 2+2=4. If you ask the question to t or f and r is next to them, there will be no response, since t ALWAYS tells the truth and f ALWAYS lies. Since they don't know what r will say, the only way not to break their rules is to not give a response.

With that understanding, let's take a scenario where the alien in position 1 is r. You ask "Would the alien in position 2 say 2+2=4?" You receive uzu or olo. Since there was a response, you can rule out the alien in position 2 being r, but the alien in position 1 might still be r. Moving to the second, you ask "Would the alien in position 3 say 2+2=4?" You receive either uzu or olo, which means that the final alien is not r, which means the first alien is r. You also know that the response you just received means no, due to the logic I presented in the above paragraph. The only step you have to do now is ask the same alien "does 2+2=4?" If the alien responds with the negative value you just learned, you know f is in position two and t in position 3. Conversely, if the alien responds with positive, you know the opposite is true

Now let's take a scenario where r is in the middle. You ask the alien in position 1 "Would the alien in position 2 say 2+2=4?" You don't receive an answer, so you know that 2 is r. Now you ask the alien in position 1 again "Would the alien in position 3 say 2+2=4?" Again, you know the answer is the equivalent of "no". So you ask alien 1 again "does 2+2=4?" If the answer is the same as the negative you just learned, position 1 is f and 3 is t, and vice-versa for a positive answer.

And now the final scenario where r is at the end. You ask the alien in position 1 "Would the alien in position 2 say 2+2=4?" You receive either uzu or olo. Since there was a response, you can rule out the alien in position 2 being r, but the alien in position 1 might still be r. Moving to the second, you ask "Would the alien in position 3 say 2+2=4? " You don't receive a response, which lets you know that the alien in position 3 is r, and that the response that the alien in position 1 gave is the equivalent to "no". Now ask the second alien "does 2+2=4?" if the alien answers with the negative, you know that 1 is t and 2 is f, and opposite for a positive answer.

So, there's my solution. You still figure out which each alien is, AND you get to find out which value is the negative and by elimination which is the positive.
Jkayppobox
Ok so they video talks about spatial questions... I got that right
Jkayppobox
That's not even hard, you just need to repeat the same positive outcome or negative outcome question twice. Then as a third question, ask who'next to who.the first question serves as a base for the 2nd question...i'm i scratching my left arm? Does the sun rise to the west? the second question same as first, defines the third alien because he has a 50% chance on this answer or the next to change answers.the third question would be an spatial one, if one's next to the other, we know who the thrid alien is already, and if who is next to him and has said the same yes answer in second and first questions then that's the first alien.
ClarkPlays ROBLOX
Better to ask the left alien this:

"If 'Yes' means Ozo, will you say Ozo?"
Andy Zachel
How do you know that the aliens can correctly answer 2+2=4? Also you didnt say what if the one you asked first is arr and his question is random...
Boy Drop out
Still confused
Right Dude Here
This would make an amazing escape room game
Luna Mint
You should have never left earth.
SENER ELTI
I wasn't paying attention I was just reading the comments...😬😉
youssef mhamed
at the end u can ask tee to say nobo if the answer is false and yoko if it true and then u can ask the question u want
red cat
There is a mistake.
If 2+2=4 and ozo =yes. Then if you ask the liar god ,"If I ask you whether 2+2=4 true will you say ozo" then he will say ulu instead of ozo.
Thats a mistake. Or I am wrong?
ri bin
it's okay if you find this confusing
even people (including me) who have the logic courses took times to understand the logic
Litsky Pancakes
NO BECAUSE YOU KEPT USING OZO TO MEAN YES BUT YOU NEVER NO WHICH ONE MEANS YES AND WHICH ONE MEANS NO YA DUMMY
Erin Lastname
Wait, how does that first question eliminate Arr? We know that Tee and Eff will answer Ozo to that question no matter what, but there's a 50% chance that Arr will as well. If it answers Ulu, we know that it's Arr. But an answer of Ozo doesn't tell us anything.
Idanos Styles
I had to write it down to understand it. Wtf so hard
sequoia perez
It hurt my brain
Mimi Nguyen
honestly ive listened to many different explanations of versions of this and i still dont understand
Shaydabop
ooooooor ask a non yes or no question.
:Pinecone
But did you know what jar belonged to which overlord? Your questions established which overlord is which, but not who their respective jar is.
민군주
This hurts my brain, but still, what there’s still that 1/3 chance that you could pick Arr to ask the question and if you’re impossibly unlucky like me, then well...
Annika van Putte
Wtaf I also had the 2 + 2 = 4 thing to identify the aliens without watching the video 😶
Cosmedian Gamer
Subbed.
HydesR01
You and your team (a dog) XD
BritishLayerSandwich
Ahh, the aliens name was T, F, and R! That means, T is True, F means False, and R is Random! I got it now!
What Did You Do To My Drink
“Can you solve the three gods riddle?”




No
Jacob Kim
You asked 4 questions
angelmushahf
I think ozo means yes
michael01123
ozo
Bbear F
Does ozo mean yes is my last question
Evan Blodgett
No way this was a hard logical question
Dory
How TF do they even understand our question?
Lovely Shasi
I can't understand the answer if u understand comment and tell the answer
ThunderFox280 Original
I have a plot twist: at 0:41, when the overlords says (or thumbs ups) the true, false, and random, Eff would've done thumbs down, thumbs, up, and hands down since he lies. Arr might tell the truth, or might be random, so if there's a random one, that that's him. Tee's would be correct, so he'd do what they all did in the video.
Sooooooooooooo, technically, it's could be easier.
God I love loopholes.
Wolffangdestiny 376
Why can’t you call out the names and see who responds then you know who is who
Aufar Rizqi
my brain hurts
황금비
그냥 당신이 왕입니까?라고 물으면 맞다 아니다라는 대답을 듣게 될 것인데 두개가 나온 답이 알과 누군가가 있다는것을 알게된다. 또 내가 외계인입니까? 등 답이 정해진 것을 물으면 답이 봐뀌는 쪽이 알
Kelly Tan
Why cant they just ask an alien citizen who is who?
plain lazy
i thought "GODS. NEVER. LIE."
TaylorMIA
What...
MartoSpidera Spidera
there is another way.You can ask them questiojs about their physical appearence
The King
But... what if Arr just so happens to randomly answer with “Ozo” or “Ulu”?
unic beast
mah brain
Naufal Khiyarulloh
Ouch! my brain.
king james488
this makes a lot of assumptions...
samuel Woodouse
heres my way 1. "would you like the truth tellers item?" truther will say $ lier will say $ so the majority answer is yes
2. did i crash land here? truther $ lier % if random responds % then we know who the truther is if the random says $ then we know who the lier is
3. ask if one of the odd two out is the truther or the lier depending on which you know and judge the knows response accordingly
get on my level TED-Ed ;)
CJ Kim
"You've deciphered the language enough to ask any questions." Instead of using the word "ozo" or "ulu" in your question (which is alien language), why not just use "yes" or "no" in English? Then they will be translated into either "ozo" and "ulu" in their language. Easy to figure out what means what.
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