# Questions tagged [blue-eyes]

For questions related to the puzzle of islanders who can only leave when they deduce the colour of their own eyes.

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### In the 100 blue eyes problem - why is the oracle necessary?

The riddle Randall Munroe (of xkcd fame) has, a bit hidden on his site, a logic puzzle: A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a ...
2k views

### In the blue-eyes puzzle, why can't they skip ahead? [duplicate]

In the solution to the Blue Eyes logic puzzle, there is a follow-up question: Each person knows, from the beginning, that there are no less than 99 blue-eyed people on the island. How, then, is ...
708 views

### Numbered Logicians near the Blue Eyes island

There is an island near the famous Blue Eyes island where 100 perfect logicians live, each with a number between 1 and 100 (repetitions allowed) tattooed on their forehead. They know all the numbers ...
656 views

### Exponential time in a Blue Eyes variant

I created a variant of the Blue Eyes problem where the logic took 4901 days (over 13 years) to totally play out. I thought this was nice, but I was hoping for an even longer period of time. Of ...
768 views

### Variants to blue eyes puzzle

Here are some variants to the Blue Eyes puzzle. All the rules are the same, but there are differences in (a) the number of people of different eye colors and (b) the oracle's statement. It is not ...
871 views

### Green Eyed Oracle Variant - Not a Multiple of $17$

$100$ perfect logicians have been gathered on an island. It is common knowledge that logicians always have blue or brown eyes, though on this island, all eyes are blue. However, there are no ...