A native, either a knight or a liar, once pointed to a man sitting below a tree and told me "If asked, that man would say I'm not the same type as he is."
What can you deduce about the native or the man?
If they were both Knights - the knight under the tree wouldn't lie by saying they were different types and the man speaking would not lie about what his fellow knight would say, so the above statement could not be made if they were both knights.
If they were both Liars - The Liar under the tree would lie and say that they were different types. But the liar who is speaking would lie about that claiming that the man under the tree would say they're the same, so the above statement could not be made if they were both knights.
If the man under the tree is a knight he would claim that they were different types, but the liar would lie about that so the above statement could not be made by a Liar talking about a Knight.
Similarly a Liar under the tree would claim that he was the same as the Knight and the Knight would accurately reflect this.
So if there is anything to be deduced, it is that these 4 configurations are all impossible (this statement would never be made) and the man under the tree must be a Knave who is getting ready to tell the truth if it is a Knight speaking or a lie if it is a Liar speaking
Posted by scott
on 2013-04-17 17:40:14