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 Summary
 Please help me understand whether it’s me who is not seeing something obvious or it’s something wrong with the problem itself.
Hello
I’m going through this book and it contains many puzzles and solutions. I’ve encountered a problem that makes no sense to me. I’d spent a considerable amount of time on it before I finally gave up and looked at the solution, where I discovered essentially the deductions identical to mine.
In the solution the author starts with an assumption that one of the two opposite possibilities is true, reasons until he encounters a contradiction, and declares that, since we encountered it, the opposite must be true.
But if you explore the opposite assumption it also leads to a contradiction. I suspect that there's is something wrong with the problem itself, but would still like a confirmation.
The problem and the solution are in attachment. And these are preliminary conditions:
There are two types of people on an island: knights and knaves. Knights always tell the truth and knaves always lie. Everyone is mute and uses cards to signal YES or NO. The cards are RED and BLACK, but we don’t know which is which.
Thanks
I’m going through this book and it contains many puzzles and solutions. I’ve encountered a problem that makes no sense to me. I’d spent a considerable amount of time on it before I finally gave up and looked at the solution, where I discovered essentially the deductions identical to mine.
In the solution the author starts with an assumption that one of the two opposite possibilities is true, reasons until he encounters a contradiction, and declares that, since we encountered it, the opposite must be true.
But if you explore the opposite assumption it also leads to a contradiction. I suspect that there's is something wrong with the problem itself, but would still like a confirmation.
The problem and the solution are in attachment. And these are preliminary conditions:
There are two types of people on an island: knights and knaves. Knights always tell the truth and knaves always lie. Everyone is mute and uses cards to signal YES or NO. The cards are RED and BLACK, but we don’t know which is which.
Thanks
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