Comments by "Limrasson" (@Limrasson) on "TED-Ed"
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Well I did solve it but since I think that I may cheated/exploited the rules or lack of them I would like if one of you who watched the video could tell me if this was the solution or not before I watch it (I would try to find the actual solution if not).
So anyway here's my solution:
Step #1 Realise that ARR (the alien that answers randomly) is a problem.
Step #2 Realise that ARR (the alien that answers randomly) is a problem for TEE (the alien that always answers the truth) and EFF (the alien that always lies) as well.
Step #3 Set goals: Find ARR, tell which answer is which, ask question you know answer from the rest.
Step #4 The exploit: if I ask an alien "Alien 1, will Alien 2 tell me the truth?" Or any variation of this question, the important part is that you ask it so that it's clear that the YES answer can only be given if Alien 2 ALWAYS tells the truth, so if TEE. Then there are 2 answers you can receive. Either there IS an answer or there is NONE. Because if you ask TEE or EFF while pointing at ARR, then you asked them a question they cannot decide the answer to. There is a chance that ARR answers the truth and there is a chance he will lie. The only one who could answer this question while pointing at ARR is ARR itself (since he doesn't give a damn), but you always ask about a different alien. So by using this...
Step #5 Ask Alien 1: "Will Alien 2 tell the truth?" If you get no answer then Alien 2 = ARR. If you get an answer, let's call it Answer "A", Alien 2 is not ARR. Now you ask Alien 2 "Will Alien 3 tell the truth?" This is a different question than the first one since the subject is different. Now if you don't get an answer, Alien 3 is ARR and answer "A" means "NO" (because if you ask a liar if the honest will be honest he will say NO and if you ask the honest the same about the liar he also says "NO") IF you get an answer "B", then B = NO and Alien 1 is ARR. With this we can decide who is ARR and then eliminate him from the game.
Step #5 The only place where we couldn't decide which answer means NO (and therefore which one means YES) is when we didn't get any answers for the first question. In that case the second question is basically the same, so you ask one of the not ARRs if the other not ARR will tell the truth. (Alien 2 is ARR because we didn't get answer to first question) To this question they'll answer "D" which will mean "NO". This way we concluded which answer means what. One one step and question remain.
Steap #6 Ask one of the not ARR's if ARR is ARR. You know the answer to this question so whoever answers "NO" is the liar and whoever answers "Yes" is the honest alien. You found all 6 solutions.
I kinda feel good about finding an exploit (I don't think I broke any rules, all questinos are YES or NO and all of them are technically different), but the solution is probably not the actual solution, now is it?
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