Inductive Logic Puzzles

Have large numbers of HN people really not seen this riddle before? Maybe I read weird things.

(This is a reference to a logic puzzle about islanders who are able to tell whether they have blue eyes due to someone telling the world that someone has blue eyes. Puzzle at http://xkcd.com/blue_eyes.html , solution at http://xkcd.com/solution.html .)

Seems like a variation on the king's wise men puzzle.

Here's XKCD's blue-eyes problem http://www.xkcd.com/blue_eyes.html and solution: http://xkcd.com/solution.html

why is it three logicians? wouldn't it work with just two?

You'd have better results if you had prompted it with the actual answer and asked how the first person came to the conclusion. Giving a number in the training set is very easy.i.e. You observe three people in a magical room. The first person is standing underneath a 65, the second person is standing underneath a 26 and the third person is standing underneath a 39. They can see the others numbers but not the one they are directly under. You tell them one of the three numbers is the sum of

I think the puzzle isn't specified well enough. Critically, it doesn't say that your friend knows whether you passed or not when you're asked, and this is a central part of the proposed solution:> First, you and your friend have to realize that each “pass” counts as a signal.But the spec only says> The caretaker asks you each one at a time, once a day, and you can choose to answer or to pass. Both of you know that you’re always asked first. If you both pass on a giv

You have to remember this is merely a logic puzzle devised to have a non-intuitive solution. The pirates thing is merely a pasted-on theme. If it helps, consider these are robots who must follow a set of predetermined rules.

If one of the possible answers is "There's not enough information to decide", that's a good hint that something weird may be going on and you should double-check your assumption of "everybody is telling the truth".

The only critical assumptions are that they are aware of the details of what both of them have been given and that if they could have known the answer they would say so (i.e. that they are being perfectly logical and not making a mistake). The fact that this eliminates potential solutions is a consequence of that and the problem as set out. The whole puzzle hinges the fact that one person not knowing the answer from the part they are given (and the knowledge that the other person does not know a