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Wednesday, July 23, 2008

Two Pots

On the right, you see a silver and a golden pot. One of these pots contains a treasure and the other one is empty. Assume that you can determine from the text prints which pot contains the treasure.
The text prints on the pots are:
The silver pot: "This pot is empty."
The golden pot: "Exactly one of these texts is true."

The Question: Which pot contains the treasure?

Answer: Assume that the print on the first (silver) pot is right.

Assume also the second print (on the golden pot) to be right.
So now we assume that both prints hold,
but this means that only one print holds (according to the second print).
This leads to a contradiction!

So the assumption that the second print holds is wrong!
This means that the second print does not hold.
So now we assume that only the first print holds,
but this would make the second print right.
Which again leads to a contradiction!

So the assumption that the first print holds is wrong!
This means that the first print does not hold. (We can also prove that the correctness of the second print is of no concern anymore.)

Conclusion: The silver pot contains the treasure!...

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