You’ve crash landed on an alien planet. The only way to get home is to give the correct artifacts to the planet’s three alien overlords: Tee, Eff, and Arr.

The challenge: Which alien overlord is which? You can find out by asking just three yes or no questions to any one alien. Tee’s answers are always true. Eff’s answers are always false. Arr’s answers are random each time. Oh, and by the way, they’ll respond with “ulu” or “ozo” to each question, so it may be a bit challenging to understand them.

Are you ready to try and solve what has been called the hardest logic puzzle ever? Pause at the 1m5s mark for the chance to figure it out! In the following three minutes, educator Alex Gendler will walk through the logic required to solve this puzzle by logician Raymond Smullyan.

Next: Try and solve more TED Ed riddles.

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